Container: Support to pass a fork repository as argument

.github/container/Dockerfile

@@ -1,4 +1,5 @@
 FROM alpine:3.15.4 AS build
+ARG REPOSITORY=https://github.com/processone/ejabberd.git
 ARG VERSION=master
 
 RUN apk upgrade --update musl \
@@ -30,7 +31,7 @@ RUN mix local.hex --force \
 
 WORKDIR ejabberd
 
-RUN git clone https://github.com/processone/ejabberd.git . \
+RUN git clone $REPOSITORY . \
     && git checkout $VERSION \
     && mv .github/container/ejabberdctl.template . \
     && ./autogen.sh \

.github/workflows/container.yml

@@ -58,6 +58,7 @@ jobs:
         uses: docker/build-push-action@v2.10.0
         with:
           build-args: |
+            REPOSITORY=https://github.com/${{ github.repository }}.git
             VERSION=${{ steps.gitdescribe.outputs.ver }}
           cache-from: type=gha
           cache-to: type=gha,mode=max