Bump golang from 1.20 to 1.22 in /event-exporter

Bumps golang from 1.20 to 1.22.

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

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

event-exporter/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM --platform=$BUILDPLATFORM golang:1.20 as builder
+FROM --platform=$BUILDPLATFORM golang:1.22 as builder
 WORKDIR ${GOPATH}/src/github.com/GoogleCloudPlatform/k8s-stackdriver/event-exporter
 COPY . ./