The pythonLocation environment variable is shown as invalid access in this context

首先重現 issue 中所示 workflow 的警告，並檢查 VS Code 的 Problems 面板中回報的診斷資訊。追蹤擴充功能如何驗證對環境變數 context 的存取；完成標準是，文件所述的 pythonLocation 用法不再產生誤報警告，同時 workflow 仍然有效。

Describe the bug

When using the pythonLocation environment variable set by the actions/setup-python action, this extension reports "Context access might be invalid" even though it is a valid environment variable documented in the official setup-python action.

To Reproduce

Steps to reproduce the behavior:

1. With this workflow:

   name: Test Workflow
   
   on:
     workflow_dispatch:
   
   jobs:
     test:
       runs-on: ubuntu-latest
       steps:
         - uses: actions/checkout@v4
         - uses: actions/setup-python@v5
           with:
             python-version: '3.12'
         - name: Cache pip
           uses: actions/cache@v4
           with:
             path: ${{ env.pythonLocation }}/.cache/pip
             key: python-${{ hashFiles('setup.py', 'pyproject.toml') }}
   

2. Open the "Problems" panel in VS Code.

3. See the error:

   Context access might be invalid: pythonLocation
   

Expected behavior

The pythonLocation environment variable, which is documented and valid when using actions/setup-python, should be recognized properly by this extension.

Screenshots

If applicable, include screenshots of the warning in the Problems panel.

Extension Version

vX.Y.Z

Additional context

• Official documentation for the pythonLocation variable: [setup-python environment variables](https://github.com/actions/setup-python#outputs-and-environment-variables).
• This warning is a false positive, as the workflow executes without issues and the variable is set correctly.
• Is this a bug or a limitation of the extension?