Update gitpod.Dockerfile

 - Move to Ruby 3.3.4
 - add graphviz as a package to install as it is missing on db migration

gitpod.Dockerfile

@@ -1,7 +1,7 @@
 FROM gitpod/workspace-postgres
 USER gitpod
 
-RUN _ruby_version=ruby-3.3.1 \
+RUN _ruby_version=ruby-3.3.4 \
     && printf "rvm_gems_path=/home/gitpod/.rvm\n" > ~/.rvmrc \
     && bash -lc "rvm reinstall ruby-${_ruby_version} && rvm use ruby-${_ruby_version} --default && gem install rails" \
     && printf "rvm_gems_path=/workspace/.rvm" > ~/.rvmrc \
@@ -11,5 +11,5 @@ RUN _ruby_version=ruby-3.3.1 \
 RUN curl https://packages.redis.io/gpg | sudo apt-key add - \
  && echo "deb https://packages.redis.io/deb $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/redis.list \
  && sudo apt-get update \
- && sudo apt-get install -y redis libvips \
+ && sudo apt-get install -y redis libvips graphviz \
  && sudo rm -rf /var/lib/apt/lists/*