Prepend PATH and check version

Author: zooba

.github/workflows/build.yml

@@ -43,9 +43,14 @@ jobs:
     - name: Set up Python 3.14.0b1
       run: |
         nuget install python -Version 3.14.0-b1 -x -o .
-        (gi .\python*\tools\python.exe).Parent | Out-File $env:GITHUB_PATH -Encoding UTF8 -Append
+        $old = Get-Content $env:GITHUB_PATH
+        (gi .\python*\tools\python.exe).Parent | Out-File $env:GITHUB_PATH -Encoding UTF8
+        $old | Out-File $env:GITHUB_PATH -Encoding UTF8 -Append
       working-directory: ${{ runner.temp }}
 
+    - name: Check Python version
+      run: python -c "import sys; sys.exit(0 if sys.version_info[:3] == (3, 14, 0) else 1)"
+
     - name: Install build dependencies
       run: python -m pip install "pymsbuild>=1.2.0b1"