workflow: Change to Python 3.12

Author: rdb

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-python@v1
       with:
-        python-version: '3.7'
+        python-version: '3.12'
     - name: Install requirements
       run: |
         pip install -r requirements.txt
@@ -30,7 +30,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-python@v1
       with:
-        python-version: '3.7'
+        python-version: '3.12'
     - name: Install requirements
       run: |
         sudo apt-get install --no-install-recommends graphviz
@@ -47,7 +47,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-python@v1
       with:
-        python-version: '3.7'
+        python-version: '3.12'
     - name: Install requirements
       run: |
         sudo apt-get install --no-install-recommends graphviz latexmk texlive-fonts-recommended texlive-latex-extra tex-gyre