ci: simplify back to single test job now that sccache caches C++ on Windows

Remove the build/test split since sccache should make Windows builds
fast enough (~5 min) that compiling per Python version is acceptable.

The diff from main is now minimal: remove path filters, add MSVC setup
+ CC/CXX env vars for sccache C++ caching on Windows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: cpsievert

.github/workflows/python.yml

@@ -5,18 +5,19 @@ on:
   pull_request:
 
 jobs:
-  build:
+  test:
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
+        python: ['3.10', '3.11', '3.12', '3.13']
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
 
       - uses: actions/setup-python@v5
         with:
-          python-version: '3.10'
+          python-version: ${{ matrix.python }}
 
       - uses: actions/setup-node@v4
         with:
@@ -54,37 +55,10 @@ jobs:
           CC: ${{ runner.os == 'Windows' && 'sccache cl' || '' }}
           CXX: ${{ runner.os == 'Windows' && 'sccache cl' || '' }}
 
-      - name: Upload wheel
-        uses: actions/upload-artifact@v4
-        with:
-          name: wheel-${{ matrix.os }}
-          path: target/wheels/ggsql-*.whl
-
-  test:
-    needs: build
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
-        python: ['3.10', '3.11', '3.12', '3.13']
-    runs-on: ${{ matrix.os }}
-    steps:
-      - uses: actions/checkout@v4
-
-      - uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python }}
-
-      - name: Download wheel
-        uses: actions/download-artifact@v4
-        with:
-          name: wheel-${{ matrix.os }}
-          path: dist
-
       - name: Install wheel and test dependencies
         shell: bash
         run: |
-          WHEEL=$(ls dist/ggsql-*.whl)
+          WHEEL=$(ls target/wheels/ggsql-*.whl)
           pip install "${WHEEL}[test]"
 
       - name: Run tests