ci: add upstream version to cache key

Author: vernette

.github/workflows/build-ipk.yml

@@ -83,7 +83,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: /builder/dl
-          key: openwrt-dl-${{ matrix.branch }}-${{ matrix.arch }}-${{ hashFiles('beszel-agent/Makefile') }}
+          key: openwrt-dl-${{ matrix.branch }}-${{ matrix.arch }}-${{ needs.validate-versions.outputs.latest_upstream_version }}-${{ hashFiles('beszel-agent/Makefile') }}
           restore-keys: |
             openwrt-dl-${{ matrix.branch }}-${{ matrix.arch }}-
             openwrt-dl-${{ matrix.branch }}-