Bump golang from 1.23.2 to 1.23.3 in /cmd

Bumps golang from 1.23.2 to 1.23.3.

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

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

cmd/Dockerfile

@@ -1,5 +1,5 @@
 #############      builder              #############
-FROM --platform=${BUILDPLATFORM} golang:1.23.2 AS builder
+FROM --platform=${BUILDPLATFORM} golang:1.23.3 AS builder
 
 WORKDIR /go/src/github.com/gardener/apiserver-proxy
 COPY . .