Remove lots of unnecessary curly braces.

Dockerfile

@@ -8,32 +8,32 @@ ARG GIT_COMMIT
 ARG GIT_REMOTE
 ARG VERSION
 
-LABEL git_commit=${GIT_COMMIT}
-LABEL git_remote=${GIT_REMOTE}
+LABEL git_commit=$GIT_COMMIT
+LABEL git_remote=$GIT_REMOTE
 LABEL maintainer="bryce.beuerlein@cisa.dhs.gov"
 LABEL vendor="Cyber and Infrastructure Security Agency"
-LABEL version=${VERSION}
+LABEL version=$VERSION
 
 ARG CISA_UID=421
 ENV CISA_HOME="/home/cisa"
 ENV GOPHISH_TOOLS_SRC="/usr/src/gophish-tools"
 
-RUN addgroup --system --gid ${CISA_UID} cisa \
-  && adduser --system --uid ${CISA_UID} --ingroup cisa cisa
+RUN addgroup --system --gid $CISA_UID cisa \
+  && adduser --system --uid $CISA_UID --ingroup cisa cisa
 
 RUN apk --update --no-cache add \
   bash \
   py-pip
 
-VOLUME ${CISA_HOME}
+VOLUME $CISA_HOME
 
-WORKDIR ${GOPHISH_TOOLS_SRC}
-COPY . ${GOPHISH_TOOLS_SRC}
+WORKDIR $GOPHISH_TOOLS_SRC
+COPY . $GOPHISH_TOOLS_SRC
 
 RUN pip install --no-cache-dir .
 RUN chmod +x ${GOPHISH_TOOLS_SRC}/var/getenv
 RUN ln -snf ${GOPHISH_TOOLS_SRC}/var/getenv /usr/local/bin
 
 USER cisa
-WORKDIR ${CISA_HOME}
+WORKDIR $CISA_HOME
 CMD ["getenv"]