Revert "Update Dockerfile"

This reverts commit a8c919fd

Dockerfile

@@ -40,6 +40,9 @@ RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys \
  && curl -sSL https://get.rvm.io | bash -s -- --autolibs=read-fail stable \
  && echo 'rvm_silence_path_mismatch_check_flag=1' >> ~/.rvmrc
 
+SHELL ["/bin/bash", "-lc"]
+CMD ["/bin/bash", "-l"]
+
 # Install Ruby
 RUN rvm install 2.6.6 \
  && rvm alias create 2.6 ruby-2.6.6 \