Update nginx Docker tag to v1.23.3

Dockerfile

@@ -6,7 +6,7 @@ WORKDIR /src
 RUN npm install \
   && npm run build
 
-FROM nginx:1.23.2-alpine as prod
+FROM nginx:1.23.3-alpine as prod
 LABEL maintainer="marco.blessing@googlemail.com"
 HEALTHCHECK  --interval=15s --timeout=5s \
   CMD wget --no-verbose --tries=1 --spider http://localhost:80/ || exit 1