🌱 Update image docker.io/library/alpine to v3.21.2

| datasource | package                  | from   | to     |
| ---------- | ------------------------ | ------ | ------ |
| docker     | docker.io/library/alpine | 3.20.3 | 3.21.2 |

images/cache/Dockerfile

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 
-FROM docker.io/library/alpine:3.20.3@sha256:1e42bbe2508154c9126d48c2b8a75420c3544343bf86fd041fb7527e017a4b4a as import-cache
+FROM docker.io/library/alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099 as import-cache
 
 RUN --mount=type=bind,target=/host-tmp \
     --mount=type=cache,target=/root/.cache \
@@ -27,7 +27,7 @@ RUN --mount=type=bind,target=/host-tmp \
       tar xzf /host-tmp/go-pkg-cache.tar.gz --no-same-owner -C /go/pkg; \
     fi
 
-FROM docker.io/library/alpine:3.20.3@sha256:1e42bbe2508154c9126d48c2b8a75420c3544343bf86fd041fb7527e017a4b4a as cache-creator
+FROM docker.io/library/alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099 as cache-creator
 RUN --mount=type=cache,target=/root/.cache \
     --mount=type=cache,target=/go/pkg \
     tar czf /tmp/go-build-cache.tar.gz -C /root/.cache/go-build . ; \