Simplify CI tox steps now that lock runner is used

The uv-venv-lock-runner disregards --skip-pkg-install, making the
two-step pattern (--notest then --skip-pkg-install) unnecessary.
Consolidate into a single tox run step.

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

Author: oschwald

.github/workflows/test.yml

@@ -28,11 +28,7 @@ jobs:
       - name: Install Python
         if: matrix.env != '3.13'
         run: uv python install --python-preference only-managed ${{ matrix.env }}
-      - name: Setup test suite
-        run: tox run -vv --notest --skip-missing-interpreters false
-        env:
-          TOX_GH_MAJOR_MINOR: ${{ matrix.env }}
       - name: Run test suite
-        run: tox run --skip-pkg-install
+        run: tox run --skip-missing-interpreters false
         env:
           TOX_GH_MAJOR_MINOR: ${{ matrix.env }}