ci: add Python 3.13 to test matrix

Run repo file checks on Python 3.13 and include 3.13 in the CI Python matrices.

Author: ringlej

.github/workflows/run-tests.yaml

@@ -91,7 +91,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
     name: Merge tests 2 - Python (${{ matrix.python-version }}) functional tests (Ubuntu)
     steps:
     - name: Checkout the code
@@ -153,7 +153,7 @@ jobs:
     - name: Setup Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.12'
+        python-version: '3.13'
 
     - name: Install zcbor
       uses: ./.github/actions/install_zcbor
@@ -248,7 +248,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
         asserts: ["", "-x VERBOSE=ON -x ASSERTS=ON"]
     name: Release tests 3 (Python ${{ matrix.python-version }}${{ matrix.asserts != '' && ' with asserts' || '' }})
     needs:
@@ -284,7 +284,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
         asserts: ["", "-x VERBOSE=ON -x ASSERTS=ON"]
     name: Release tests 4 (Python ${{ matrix.python-version }}${{ matrix.asserts != '' && ' with asserts' || '' }})
     needs: