Improve error message when using 3.x with 1.x changes.xml file

从 ChangesXML.java 开始，使用报告的 1.x changes.xml 示例进行复现，并沿着 ChangesXpp3Reader.parseAction 的解析路径跟踪。检查如何读取所引用的 namespace，以及如何包装解析失败。完成的标准是：不支持的 Changes 文件版本会产生明确的、与版本相关的错误，而不是通用的 XML 解析器消息。

New feature, improvement proposal

I received the following confusing error message when using my old changes file (sticking to https://maven.apache.org/xsd/changes-1.0.0.xsd)

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.21.0:site (default-site) on project ...: Failed to render site: Error generating maven-changes-plugin:3.0.0-M3:changes-report report: An error occurred when parsing the changes.xml file: TEXT must be immediately followed by END_TAG and not START_TAG (position: START_TAG seen ...   Deleted the erroneous code.\n        <fixes issue="MCHANGES-1"/>... @38:36) -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.21.0:site (default-site) on project different-doxia-versions: Failed to render site

...
Caused by: org.apache.maven.plugins.changes.ChangesXMLRuntimeException: An error occurred when parsing the changes.xml file
    at org.apache.maven.plugins.changes.ChangesXML.<init> (ChangesXML.java:100)
    at org.apache.maven.plugins.changes.ChangesReport.getChangesFromFile (ChangesReport.java:372)
    at org.apache.maven.plugins.changes.ChangesReport.executeReport (ChangesReport.java:216)
    at org.apache.maven.reporting.AbstractMavenReport.generate (AbstractMavenReport.java:358)
    at org.apache.maven.plugins.site.render.ReportDocumentRenderer.renderDocument (ReportDocumentRenderer.java:199)
    at org.apache.maven.doxia.siterenderer.DefaultSiteRenderer.render (DefaultSiteRenderer.java:302)
    at org.apache.maven.plugins.site.render.SiteMojo.renderNonDoxiaDocuments (SiteMojo.java:282)
    at org.apache.maven.plugins.site.render.SiteMojo.renderLocale (SiteMojo.java:147)
    at org.apache.maven.plugins.site.render.SiteMojo.execute (SiteMojo.java:112)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:919)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:285)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:207)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:103)
    at java.lang.reflect.Method.invoke (Method.java:580)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: org.codehaus.plexus.util.xml.pull.XmlPullParserException: TEXT must be immediately followed by END_TAG and not START_TAG (position: START_TAG seen ...   Deleted the erroneous code.\n        <fixes issue="MCHANGES-1"/>... @38:36) 
    at org.codehaus.plexus.util.xml.pull.MXParser.nextText (MXParser.java:1108)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.parseAction (ChangesXpp3Reader.java:747)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.parseRelease (ChangesXpp3Reader.java:1098)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.parseBody (ChangesXpp3Reader.java:827)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.parseChangesDocument (ChangesXpp3Reader.java:880)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.read (ChangesXpp3Reader.java:606)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.read (ChangesXpp3Reader.java:637)
    at org.apache.maven.plugins.changes.model.io.xpp3.ChangesXpp3Reader.read (ChangesXpp3Reader.java:668)
    at org.apache.maven.plugins.changes.ChangesXML.<init> (ChangesXML.java:74)

It would be nice to have a more explicit error message which derives from the referenced namespace that the issue is caused by a non supported Changes file version.