Bump setup-python and use 3.9 for typechecking

Author: fantix

.github/workflows/tests.yml

@@ -20,9 +20,9 @@ jobs:
         submodules: true
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@f677139bbe7f9c59b41e40162b753c062f5d49a3  # v5.2.0
+      uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
       with:
-        python-version: "3.8"
+        python-version: "3.9"
 
     - name: Type check
       run: make typecheck
@@ -55,7 +55,7 @@ jobs:
           __version__\s*=\s*(?:['"])([[:PEP440:]])(?:['"])
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@f677139bbe7f9c59b41e40162b753c062f5d49a3  # v5.2.0
+      uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
       if: steps.release.outputs.version == 0
       with:
         python-version: ${{ matrix.python-version }}