Use uv on GitHub Actions (#645)

Gives a nice speed boost.

Author: adamchainz

.github/workflows/main.yml

@@ -31,13 +31,14 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
         allow-prereleases: true
-        cache: pip
-        cache-dependency-path: 'requirements/*.txt'
+
+    - name: Install uv
+      uses: astral-sh/setup-uv@v1
+      with:
+        enable-cache: true
 
     - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip setuptools wheel
-        python -m pip install --upgrade 'tox>=4.0.0rc3'
+      run: uv pip install --system tox tox-uv
 
     - name: Run tox targets for ${{ matrix.python-version }}
       run: tox run -f py$(echo ${{ matrix.python-version }} | tr -d .)
@@ -61,8 +62,11 @@ jobs:
         with:
           python-version: '3.12'
 
+      - name: Install uv
+        uses: astral-sh/setup-uv@v1
+
       - name: Install dependencies
-        run: python -m pip install --upgrade coverage[toml]
+        run: uv pip install --system coverage[toml]
 
       - name: Download data
         uses: actions/download-artifact@v4