feat: Update CircleCI configuration file

hooks/build

@@ -3,10 +3,10 @@
 # Docker Daemon Build Hook
 # $IMAGE_NAME var is injected into the build so the tag is correct.
 
-docker pull ${DOCKER_REPO}:latest
+docker pull "${DOCKER_REPO}:latest"
 
 docker build \
-        --cache-from=${DOCKER_REPO}:latest \
+        --cache-from="${DOCKER_REPO}:latest" \
         --build-arg=BUILD_DATE="$(date +"%Y-%m-%d %H:%M:%S%:z")" \
 		--build-arg=VCS_REF="$(git rev-parse --short HEAD)" \
-		-t ${IMAGE_NAME} .
+		-t "${IMAGE_NAME}" .