fix: update docker file for ruby version 2.6

Dockerfile

@@ -1,33 +1,15 @@
 FROM ruby:2.6
 
-RUN gem install bundler
-
-RUN apt-get update -qq
-# Add https support to apt to download yarn & newer node
-RUN apt-get install -y  apt-transport-https
-
-# Add yarn repo and install along with other rails deps
-RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
-RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
 RUN apt-get update -qq
 RUN apt-get install mariadb-client build-essential libpq-dev yarn nodejs chromium-driver libatk-bridge2.0-0 libgtk-3.0 -y
 
 WORKDIR /ursus
 
-# Install Ruby Gems
-ENV BUNDLE_PATH /usr/local/bundle
 COPY Gemfile ./Gemfile
 COPY Gemfile.lock ./Gemfile.lock
 RUN bundle install
 
-# node stuff is currently dev only
-# # Install node packages
-# COPY ./package.json ./package.json
-# COPY ./yarn.lock ./yarn.lock
-# RUN yarn install --frozen-lockfile
-
-# Add sinaimanuscripts site
 # COPY / /sinai
-CMD ["sh", "./start-sinai.sh"]
+CMD ["bundle", "exec", "rails", "s", "-b", "0.0.0.0"]
 
-EXPOSE 3000
+EXPOSE 3000