build(deps): Bump golang from 1.21.3 to 1.21.4

Bumps golang from 1.21.3 to 1.21.4.

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

Signed-off-by: dependabot[bot] <support@github.com>

Dockerfile

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.21.3@sha256:02d7116222536a5cf0fcf631f90b507758b669648e0f20186d2dc94a9b419a9b AS builder
+FROM golang:1.21.4@sha256:81cd210ae58a6529d832af2892db822b30d84f817a671b8e1c15cff0b271a3db AS builder
 ENV APP_ROOT=/opt/app-root
 ENV GOPATH=$APP_ROOT
 
@@ -31,7 +31,7 @@ RUN CGO_ENABLED=0 go build -gcflags "all=-N -l" -ldflags "${SERVER_LDFLAGS}" -o
 RUN go test -c -ldflags "${SERVER_LDFLAGS}" -cover -covermode=count -coverpkg=./... -o rekor-server_test ./cmd/rekor-server
 
 # Multi-Stage production build
-FROM golang:1.21.3@sha256:02d7116222536a5cf0fcf631f90b507758b669648e0f20186d2dc94a9b419a9b as deploy
+FROM golang:1.21.4@sha256:81cd210ae58a6529d832af2892db822b30d84f817a671b8e1c15cff0b271a3db as deploy
 
 # Retrieve the binary from the previous stage
 COPY --from=builder /opt/app-root/src/rekor-server /usr/local/bin/rekor-server