Fix hadolint warning

https://github.com/hadolint/hadolint/wiki/DL3059

Author: kemsakurai

Dockerfile

@@ -3,9 +3,8 @@ FROM openjdk:17-alpine
 ENV REVIEWDOG_VERSION=v0.14.1
 
 RUN wget -O - -q https://raw.githubusercontent.com/reviewdog/reviewdog/master/install.sh | sh -s -- -b /usr/local/bin/ ${REVIEWDOG_VERSION}
-
-RUN wget -q https://github.com/pmd/pmd/releases/download/pmd_releases%2F6.51.0/pmd-bin-6.51.0.zip
-RUN unzip pmd-bin-6.51.0.zip
+RUN wget -q https://github.com/pmd/pmd/releases/download/pmd_releases%2F6.51.0/pmd-bin-6.51.0.zip \
+ && unzip pmd-bin-6.51.0.zip
 
 RUN apk add --no-cache git