Use consistent case for AS in Dockerfile

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:hydrogen-alpine as base
+FROM node:hydrogen-alpine AS base
 
 WORKDIR /usr/src/app
 
@@ -9,7 +9,7 @@ RUN deluser --remove-home node \
  && addgroup -S node -g 10000 \
  && adduser -S -G node -u 10000 node
 
-FROM base as build
+FROM base AS build
 
 COPY package-lock.json ./
 COPY package.json ./
@@ -20,7 +20,7 @@ RUN chmod u+x ./server.js
 RUN npm pack
 RUN tar -xzf *.tgz
 
-FROM base as install
+FROM base AS install
 
 ENV NODE_ENV=production
 
@@ -29,7 +29,7 @@ COPY package.json ./
 RUN --mount=type=cache,target=/root/.npm npm ci
 RUN rm package.json package-lock.json
 
-FROM base as app
+FROM base AS app
 
 COPY --from=install /usr/src/app .
 COPY --from=build /usr/src/app/package .