Bump alpine to 3.23, add platforms to docker-dryrun (#36379)

- Bump alpine to 3.23 following
https://github.com/go-gitea/gitea/pull/36185 and
https://github.com/go-gitea/gitea/pull/36202.
- Enable all architectures in `docker-dryrun`.
- Tweak actions conditions to be more precise.

---------

Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.com>
Co-authored-by: Giteabot <teabot@gitea.io>

Dockerfile.rootless

@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 # Build stage
-FROM docker.io/library/golang:1.25-alpine3.22 AS build-env
+FROM docker.io/library/golang:1.25-alpine3.23 AS build-env
 
 ARG GOPROXY=direct
 
@@ -33,7 +33,7 @@ COPY docker/rootless /tmp/local
 RUN chmod 755 /tmp/local/usr/local/bin/* \
               /go/src/code.gitea.io/gitea/gitea
 
-FROM docker.io/library/alpine:3.22 AS gitea-rootless
+FROM docker.io/library/alpine:3.23 AS gitea-rootless
 
 EXPOSE 2222 3000