Bump the docker-bacsicauth group in /cmd/githubauth with 2 updates (#93)

Bumps the docker-bacsicauth group in /cmd/githubauth with 2 updates: golang and alpine.


Updates `golang` from 1.23.3 to 1.23.4

Updates `alpine` from 3.20.3 to 3.21.0

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

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

cmd/githubauth/Dockerfile

@@ -1,11 +1,11 @@
-FROM golang:1.23.3 AS build
+FROM golang:1.23.4 AS build
 WORKDIR /githubauth
 COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
 RUN export CGO_ENABLED=0 && make build-githubauth
 
-FROM alpine:3.20.3
+FROM alpine:3.21.0
 RUN apk update && apk add --no-cache ca-certificates
 RUN mkdir /githubauth
 COPY --from=build /githubauth/bin/githubauth /githubauth