Enhancement: Build Docker image based on PHAR

Dockerfile

@@ -4,16 +4,15 @@ LABEL "repository"="https://github.com/ergebnis/composer-normalize-action"
 LABEL "homepage"="https://github.com/ergebnis/composer-normalize"
 LABEL "maintainer"="Andreas Möller <[email protected]>"
 
-COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer
-
-ENV COMPOSER_ALLOW_SUPERUSER=1
-
-RUN composer global require ergebnis/composer-normalize:2.2.0 --no-interaction --no-progress --no-suggest
-
-RUN mkdir /app
-
-WORKDIR /app
-
-ENTRYPOINT ["/usr/local/bin/composer", "normalize"]
-
-CMD ["--dry-run"]
+ENV VERSION=2.5.1
+
+RUN apk add --no-cache gnupg \
+    && cd /opt/ \
+    && wget https://github.com/ergebnis/composer-normalize/releases/download/${VERSION}/composer-normalize.phar.asc \
+    && wget https://github.com/ergebnis/composer-normalize/releases/download/${VERSION}/composer-normalize.phar \
+    && gpg --yes --keyserver pool.sks-keyservers.net --recv-keys 0FDE18AE1D09E19F60F6B1CBC00543248C87FB13 \
+    && gpg --yes --verify composer-normalize.phar.asc composer-normalize.phar \
+    && chmod +x composer-normalize.phar \
+    && mv composer-normalize.phar /usr/bin/composer-normalize
+
+ENTRYPOINT ["/usr/bin/composer-normalize"]

Makefile

@@ -1,5 +1,6 @@
 .PHONY: docker help it
 
+COMPOSER_NORMALIZE_VERSION:=2.5.1
 DOCKER_IMAGE:=ergebnis/composer-normalize-action
 
 it: docker ## Runs the docker target