CI: Update cache action to v4 (#4275)

Author: abravalheri

.github/workflows/main.yml

@@ -69,7 +69,7 @@ jobs:
         with:
           python-version: ${{ matrix.python }}
           allow-prereleases: true
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         id: cache
         with:
           path: setuptools/tests/config/downloads/*.cfg