Bump the docker-dependencies group with 2 updates (#188)

Bumps the docker-dependencies group with 2 updates: golang and alpine.


Updates `golang` from 1.20.6 to 1.21.0

Updates `alpine` from 3.18.2 to 3.18.3

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: docker-dependencies
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: docker-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Dockerfile

@@ -1,9 +1,9 @@
-FROM golang:1.20.6
+FROM golang:1.21.0
 COPY ./ /exporter/
 WORKDIR /exporter
 RUN make build-linux
 
-FROM alpine:3.18.2
+FROM alpine:3.18.3
 RUN apk add --no-cache ca-certificates
 COPY --from=0 /exporter/bin/linux_amd64/aws-apigateway-exporter \
     /bin/aws-apigateway-exporter