Fix shellcheck

Signed-off-by: Florian Hotze <dev@florianhotze.com>

Author: florian-h05

alpine/Dockerfile

@@ -62,7 +62,7 @@ RUN apk update --no-cache && \
         wget \
         zip && \
     # Install NodeJS only for openHAB >= 5
-    if [ $(echo "$OPENHAB_VERSION" | sed -E 's/^([0-9]+).*/\1/') -ge 5 ]; then apk add --no-cache nodejs; fi && \
+    if [ "$(echo "$OPENHAB_VERSION" | sed -E 's/^([0-9]+).*/\1/')" -ge 5 ]; then apk add --no-cache nodejs; fi && \
     chmod u+s /usr/sbin/arping && \
     rm -rf /var/cache/apk/*