Remove Rails 5 workarounds

These where put in to support Rails 5 integration tests, which have
been removed.

Author: mec

Dockerfile

@@ -12,12 +12,9 @@ FROM base as build
 RUN apt-get update -qq && \
     apt-get install --no-install-recommends -y build-essential curl git
 
-# Install Nokigiri version that supports Ruby 2.7.8
-RUN gem install nokogiri -v 1.15.6
-
 # add a newer version of Rubygems and Bundler
-RUN gem install bundler:2.3.22
-RUN gem update --system 3.3.22
+RUN gem update --system
+RUN gem install bundler
 
 # Install Rails
 ARG RAILS_VERSION=7.1.3.2
@@ -31,9 +28,6 @@ WORKDIR mail-notify-integration
 # install the gems into the bundle
 RUN bundle install
 
-# remove gems that will not work in Rails 5.2.8.1
-RUN if [ "${RAILS_VERSION}" = "5.2.8.1" ]; then bundle remove selenium-webdriver chromedriver-helper; fi
-
 # Final stage for app image
 FROM base