Use quotes in labels for consistency

dockerfile

@@ -20,15 +20,15 @@ FROM node:14-bullseye-slim AS release
 
 ARG BUILD_DATE
 
-LABEL org.opencontainers.image.authors='Louis Lam' \
-      org.opencontainers.image.url='https://uptime.kuma.pet' \
-      org.opencontainers.image.documentation='https://github.com/louislam/uptime-kuma/wiki' \
-      org.opencontainers.image.source='https://github.com/louislam/uptime-kuma.git' \
-      org.opencontainers.image.vendor='Louis Lam' \
-      org.opencontainers.image.licenses='MIT License' \
+LABEL org.opencontainers.image.authors="Louis Lam" \
+      org.opencontainers.image.url="https://uptime.kuma.pet" \
+      org.opencontainers.image.documentation="https://github.com/louislam/uptime-kuma/wiki" \
+      org.opencontainers.image.source="https://github.com/louislam/uptime-kuma.git" \
+      org.opencontainers.image.vendor="Louis Lam" \
+      org.opencontainers.image.licenses="MIT License" \
       org.opencontainers.image.title="Uptime Kuma" \
       org.opencontainers.image.description="Self-hosted uptime monitoring tool with notifications" \
-      org.opencontainers.image.created=$BUILD_DATE
+      org.opencontainers.image.created="$BUILD_DATE"
 
 WORKDIR /app
 

dockerfile-alpine

@@ -20,15 +20,15 @@ FROM node:14-alpine3.12 AS release
 
 ARG BUILD_DATE
 
-LABEL org.opencontainers.image.authors='Louis Lam' \
-      org.opencontainers.image.url='https://uptime.kuma.pet' \
-      org.opencontainers.image.documentation='https://github.com/louislam/uptime-kuma/wiki' \
-      org.opencontainers.image.source='https://github.com/louislam/uptime-kuma.git' \
-      org.opencontainers.image.vendor='Louis Lam' \
-      org.opencontainers.image.licenses='MIT License' \
+LABEL org.opencontainers.image.authors="Louis Lam" \
+      org.opencontainers.image.url="https://uptime.kuma.pet" \
+      org.opencontainers.image.documentation="https://github.com/louislam/uptime-kuma/wiki" \
+      org.opencontainers.image.source="https://github.com/louislam/uptime-kuma.git" \
+      org.opencontainers.image.vendor="Louis Lam" \
+      org.opencontainers.image.licenses="MIT License" \
       org.opencontainers.image.title="Uptime Kuma" \
       org.opencontainers.image.description="Self-hosted uptime monitoring tool with notifications" \
-      org.opencontainers.image.created=$BUILD_DATE
+      org.opencontainers.image.created="$BUILD_DATE"
 
 WORKDIR /app