Use devenv in GitHub test actions

This will install all Python versions, run linting and run tests for
all versions.

.github/workflows/test.yml

@@ -7,27 +7,27 @@ on: [push, pull_request]
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
+
     strategy:
       fail-fast: false
-      matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
-    - uses: actions/checkout@v4
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v4
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: |
-          python -m pip install --upgrade pip
-          pip install poetry
-          poetry install --all-extras
-    - name: Pre-commit checks
-      run: |
-        poetry run pre-commit run -a
-    - name: Test
-      run: |
-        poetry run pytest
+      - uses: actions/checkout@v4
+
+      - uses: cachix/install-nix-action@v26
+
+      - uses: cachix/cachix-action@v14
+        with:
+          name: devenv
+
+      - name: Install devenv.sh
+        run: |
+          nix profile install nixpkgs#devenv
+          devenv just install-versions
+
+      - name: Check linting, formatting
+        run: devenv shell just check
+
+      - name: Run all tests
+        run: devenv shell just test-all