disable GIL to run test suite

.github/workflows/test.yml

@@ -93,6 +93,10 @@ jobs:
       - name: Install older AnyIO in Python 3.8
         if: matrix.python-version == '3.8'
         run: uv pip install "anyio[trio]<4.0.0"
+      - name: Set PYTHON_GIL
+          if: endsWith(matrix.python-version, 't')
+          run: |
+            echo "PYTHON_GIL=0" >> "$GITHUB_ENV"
       - run: mkdir coverage
       - name: Test
         run: bash scripts/test.sh