fix: install helm cm-push plugin from upstream

Dockerfile

@@ -1,13 +1,3 @@
-FROM docker.io/library/golang:1.17.6-alpine AS helm-push-plugin
-
-RUN apk update && \
-    apk upgrade && \
-    apk add make git
-
-RUN git clone https://github.com/volker-raschek/helm-push && \
-    make --directory /go/helm-push build_linux && \
-    cp /go/helm-push/bin/linux/$(go env GOARCH)/helm-cm-push /go/helm-push/helm-cm-push
-
 FROM docker.io/library/alpine:3.14
 
 ARG HELM_VERSION
@@ -15,10 +5,7 @@ ARG HELM_VERSION
 COPY install.sh /install.sh
 RUN VERSION=${HELM_VERSION} /install.sh
 
-# TODO: Until the following issue is not fixed, it is not possible to install
-# cm-push on other target architectures instead of amd64. Use instead the
-# precompiled binary.
-# https://github.com/chartmuseum/helm-push/issues/128
-COPY --from=helm-push-plugin /go/helm-push/helm-cm-push /usr/bin/helm-cm-push
+# Install additionally cm-push plugin
+RUN helm plugin install https://github.com/chartmuseum/helm-push.git
 
 ENTRYPOINT [ "/usr/bin/helm" ]