Bump alpine from 3.19.1 to 3.20.0 in /cluster/images

Bumps alpine from 3.19.1 to 3.20.0.

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

cluster/images/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.19.1
+FROM alpine:3.20.0
 
 ARG BINARY
 

cluster/images/buildx.Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.19.1
+FROM alpine:3.20.0
 
 ARG BINARY
 ARG TARGETPLATFORM