Test Alpine Linux on CI

With only one version of Python, currently 3.11.

.github/workflows/alpine-test.yml

@@ -0,0 +1,56 @@
+name: test-alpine
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    container:
+      image: alpine:latest
+
+    defaults:
+      run:
+        shell: sh -exo pipefail {0}
+
+    steps:
+    - name: Install Alpine Linux packages
+      run: |
+        apk add git git-daemon python3 py3-pip
+
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Prepare this repo for tests
+      run: |
+        ./init-tests-after-clone.sh
+
+    - name: Set git user identity and command aliases for the tests
+      run: |
+        git config --global user.email "[email protected]"
+        git config --global user.name "Travis Runner"
+        # If we rewrite the user's config by accident, we will mess it up
+        # and cause subsequent tests to fail
+        cat test/fixtures/.gitconfig >> ~/.gitconfig
+
+    - name: Update PyPA packages
+      run: |
+        # Get the latest pip, wheel, and prior to Python 3.12, setuptools.
+        python -m pip install -U pip $(pip freeze --all | grep -ow ^setuptools) wheel
+
+    - name: Install project and test dependencies
+      run: |
+        pip install ".[test]"
+
+    - name: Show version and platform information
+      run: |
+        uname -a
+        command -v git python
+        git version
+        python --version
+        python -c 'import os, sys; print(f"sys.platform={sys.platform!r}, os.name={os.name!r}")'
+
+    - name: Test with pytest
+      run: |
+        pytest --color=yes -p no:sugar --instafail -vv