fix: run docker with root to fix crashing on Linux (undoes 62da387d3a) (#525)

Dockerfile

@@ -1,10 +1,5 @@
 FROM ruby:2.7.1-alpine3.12
 
-ARG UID=1000
-ARG GID=1000
-
-RUN addgroup -S webapp -g $GID && adduser -D -S webapp -G webapp -u $UID
-
 RUN apk add --update --no-cache \
     alpine-sdk \
     nodejs-current \
@@ -16,19 +11,15 @@ RUN apk add --update --no-cache \
 
 WORKDIR /app/
 
-RUN chown -R $UID:$GID .
+COPY package.json yarn.lock Gemfile Gemfile.lock /app/
 
-USER webapp
-
-COPY --chown=$UID:$GID package.json yarn.lock Gemfile Gemfile.lock /app/
-
-COPY --chown=$UID:$GID vendor /app/vendor
+COPY vendor /app/vendor
 
 RUN yarn install --pure-lockfile
 
 RUN gem install bundler && bundle install
 
-COPY --chown=$UID:$GID . /app/
+COPY . /app/
 
 RUN yarn bundle