[Repo Assist] ci: update GitHub Actions to latest versions (checkout@v4, setup-dotnet@v4)

Review .github/workflows/build.yml, .github/workflows/build-and-pack-nightly.yml, and .github/workflows/release.yml for the action versions and deprecated output command listed in the issue. Update the specified workflow references, then inspect the resulting YAML and workflow diff; done means all listed outdated actions and the deprecated command are replaced without changing other workflow behavior.

🤖 This is an automated pull request from Repo Assist.

Problem

Several GitHub Actions workflow files were using outdated action versions and a deprecated workflow command:

actions/checkout@v4 has been available since September 2023, and actions/setup-dotnet@v4 since early 2024. The ::set-output workflow command was deprecated in GitHub Actions in October 2022 and replaced by writing to $GITHUB_OUTPUT.

Changes

• actions/checkout@v3 → @v4 in all three workflow files
• actions/setup-dotnet@v2 → @v4 in build-and-pack-nightly.yml
• echo "::set-output name=date::..." → echo "date=..." >> $GITHUB_OUTPUT in build-and-pack-nightly.yml

Benefits

• Resolves Node.js 16 deprecation warnings from checkout@v3 (GitHub Actions now requires Node.js 20+)
• Eliminates deprecated ::set-output warnings that appear in nightly build logs
• Stays current with upstream security patches in these actions

Test Status

Workflow-only change — no source code or tests modified. No local build/test run needed.
These changes are safe; checkout@v4 and setup-dotnet@v4 are drop-in replacements with the same interface.

Generated by Repo Assist · ◷

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/repo-assist.md@346204513ecfa08b81566450d7d599556807389f

[!WARNING]
🛡️ Protected Files — Push Permission Denied

This was originally intended as a pull request, but the patch modifies protected files: .github/workflows/build-and-pack-nightly.yml, .github/workflows/build.yml, .github/workflows/release.yml.

The push was rejected because GitHub Actions does not have workflows permission to push these changes, and is never allowed to make such changes, or other authorization being used does not have this permission. A human must create the pull request manually.

To create a pull request with the changes:

# Download the patch from the workflow run
gh run download 23198566450 -n agent-artifacts -D /tmp/agent-artifacts-23198566450

# Create a new branch
git checkout -b repo-assist/eng-update-github-actions-2026-03-17-90a5c06e08ef963f main

# Apply the patch (--3way handles cross-repo patches)
git am --3way /tmp/agent-artifacts-23198566450/aw-repo-assist-eng-update-github-actions-2026-03-17.patch

# Push the branch and create the pull request
git push origin repo-assist/eng-update-github-actions-2026-03-17-90a5c06e08ef963f
gh pr create --title '[Repo Assist] ci: update GitHub Actions to latest versions (checkout@v4, setup-dotnet@v4)' --base main --head repo-assist/eng-update-github-actions-2026-03-17-90a5c06e08ef963f --repo ionide/FsAutoComplete