chore(deps): bump alpine from `21dc606` to `56fa17d` in /hack/api-docs (#4286)

Bumps alpine from `21dc606` to `56fa17d`.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Moritz Johner <moolen@users.noreply.github.com>

hack/api-docs/Dockerfile

@@ -11,7 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.21@sha256:21dc6063fd678b478f57c0e13f47560d0ea4eeba26dfc947b2a4f81f686b9f45
+FROM alpine:3.21@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099
 RUN apk add -U --no-cache \
     bash \
     diffutils \