GH Actions/tests: tweak a condition (again)

... to hopefully prevent the script from throwing a parse error on Windows.

Author: jrfnl

.github/workflows/test.yml

@@ -214,6 +214,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Setup ini config
+        if: ${{ matrix.os == 'windows-latest' }}
         id: set_ini
         run: |
           # Set the "short_open_tag" ini to make sure specific conditions are tested.