Bump golang from 1.21.2-alpine3.17 to 1.21.3-alpine3.17

Bumps golang from 1.21.2-alpine3.17 to 1.21.3-alpine3.17.

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

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

Dockerfile

@@ -2,7 +2,7 @@ ARG IMAGE=scratch
 ARG OS=linux
 ARG ARCH=amd64
 
-FROM golang:1.21.2-alpine3.17 as builder
+FROM golang:1.21.3-alpine3.17 as builder
 
 WORKDIR /go/src/github.com/eko/pihole-exporter
 COPY . .