Update GitHub Actions (#1310)

Author: cclauss

.github/workflows/ci.yml

@@ -10,7 +10,6 @@ jobs:
   tox:
     runs-on: ubuntu-latest
     strategy:
-      max-parallel: 5
       matrix:
         python-version:
         - "3.10"
@@ -21,8 +20,8 @@ jobs:
         - "pypy3.11"
 
     steps:
-    - uses: actions/checkout@v2
-    - uses: actions/setup-python@v5
+    - uses: actions/checkout@v6
+    - uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install tox