ci: update python versions

(try to) use semver x-ranges in order to avoid needing manual updates of
this in the future

.github/workflows/ci.yaml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         platform: [ubuntu-latest, windows-latest]
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11-dev']
+        python-version: ['3.7', '3.8', '3.9', '3.x', '3.12-dev']
 
     env:
       PY_COLORS: 1
@@ -45,17 +45,17 @@ jobs:
           sudo apt install ffmpeg  # For replaygain
 
       - name: Test older Python versions with tox
-        if: matrix.python-version != '3.10' && matrix.python-version != '3.11-dev'
+        if: matrix.python-version != '3.x' && matrix.python-version != '3.12-dev'
         run: |
           tox -e py-test
 
       - name: Test latest Python version with tox and get coverage
-        if: matrix.python-version == '3.10'
+        if: matrix.python-version == '3.x'
         run: |
           tox -vv -e py-cov
 
       - name: Test latest Python version with tox and mypy
-        if: matrix.python-version == '3.10'
+        if: matrix.python-version == '3.x'
         # continue-on-error is not ideal since it doesn't give a visible
         # warning, but there doesn't seem to be anything better:
         # https://github.com/actions/toolkit/issues/399
@@ -64,7 +64,7 @@ jobs:
           tox -vv -e py-mypy
 
       - name: Test nightly Python version with tox
-        if: matrix.python-version == '3.11-dev'
+        if: matrix.python-version == '3.12-dev'
         # continue-on-error is not ideal since it doesn't give a visible
         # warning, but there doesn't seem to be anything better:
         # https://github.com/actions/toolkit/issues/399
@@ -73,7 +73,7 @@ jobs:
           tox -e py-test
 
       - name: Upload code coverage
-        if: matrix.python-version == '3.10'
+        if: matrix.python-version == '3.x'
         run: |
           pip install codecov || true
           codecov || true
@@ -87,10 +87,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up Python 3.10
+      - name: Set up Python 3.x
         uses: actions/setup-python@v2
         with:
-          python-version: '3.10'
+          python-version: '3.x'
 
       - name: Install base dependencies
         run: |
@@ -109,10 +109,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up Python 3.10
+      - name: Set up Python 3.x
         uses: actions/setup-python@v2
         with:
-          python-version: '3.10'
+          python-version: '3.x'
 
       - name: Install base dependencies
         run: |