github: separate build and test workflows

.github/workflows/tests.yaml

@@ -29,9 +29,9 @@ jobs:
       - name: Cache virtual environment
         uses: actions/cache@v3
         with:
-          # TODO: we are hashing requirements.txt but that doesn't contain all
-          # our dependencies pinned.
-          key: venv-${{ runner.os }}-${{ steps.setup_python.outputs.python-version}}-${{ hashFiles('requirements.txt') }}
+          # We are hashing requirements-dev.txt and requirements-extra.txt which
+          # contain all dependencies needed to run the tests and examples.
+          key: venv-${{ runner.os }}-${{ steps.setup_python.outputs.python-version}}-${{ hashFiles('requirements.txt') }}-${{ hashFiles('requirements-dev.txt') }}
           path: .venv
       - name: Install system packages
         run: sudo apt-get install -y portaudio19-dev
@@ -42,17 +42,8 @@ jobs:
         run: |
           source .venv/bin/activate
           python -m pip install --upgrade pip
-          pip install -r requirements.txt
-      - name: Build project
-        run: |
-          source .venv/bin/activate
-          python -m build
-      - name: Install project and other Python dependencies
-        run: |
-          source .venv/bin/activate
-          pip install --editable .
+          pip install -r requirements.txt -r requirements-dev.txt
       - name: Test with pytest
         run: |
           source .venv/bin/activate
-          pip install pytest
           pytest --doctest-modules --ignore-glob="*to_be_updated*" src tests