TST: test Python 3.13 both GIL and free-threading flavors

.github/workflows/bleeding_edge.yml

@@ -17,15 +17,28 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 20
 
+    strategy:
+      matrix:
+        python-version:
+        - '3.13'
+        free-threading:
+        - false
+        - true
+
     steps:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0
 
-    - name: Set up Python
-      uses: actions/setup-python@v5
+    - uses: actions/setup-python@v5
+      if: !matrix.free-threading
+      with:
+        python-version: ${{ matrix.python-version }}
+    - uses: deadsnakes/[email protected]
+      if: matrix.free-threading
       with:
-        python-version: 3.12-dev
+        python-version: ${{ matrix.python-version }}
+        nogil: true
 
     - name: Install dependencies
       run: |