build(deps): Bump golang from 1.21.5 to 1.21.6

Bumps golang from 1.21.5 to 1.21.6.

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

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

Dockerfile

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.21.5@sha256:672a2286da3ee7a854c3e0a56e0838918d0dbb1c18652992930293312de898a6 AS builder
+FROM golang:1.21.6@sha256:6fbd2d3398db924f8d708cf6e94bd3a436bb468195daa6a96e80504e0a9615f2 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:1.21.5@sha256:672a2286da3ee7a854c3e0a56e0838918d0dbb1c18652992930293312de898a6 as deploy
+FROM golang:1.21.6@sha256:6fbd2d3398db924f8d708cf6e94bd3a436bb468195daa6a96e80504e0a9615f2 as deploy
 
 # Retrieve the binary from the previous stage
 COPY --from=builder /opt/app-root/src/rekor-server /usr/local/bin/rekor-server