Combine the label

Author: MilesChou

Dockerfile

@@ -1,8 +1,8 @@
 FROM composer:latest
 
-LABEL repository="https://github.com/MilesChou/composer-action"
-LABEL homepage="https://github.com/MilesChou/composer-action"
-LABEL maintainer="MilesChou <jangconan@gmail.com>"
+LABEL repository="https://github.com/MilesChou/composer-action" \
+    homepage="https://github.com/MilesChou/composer-action" \
+    maintainer="MilesChou <jangconan@gmail.com>"
 
 RUN set -xe && \
         composer global require hirak/prestissimo && \