Update Dockerfile

Dockerfile

@@ -43,10 +43,11 @@ RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys \
 SHELL ["/bin/bash", "-lc"]
 CMD ["/bin/bash", "-l"]
 
+ENV PATH="/usr/local/rvm/gems/ruby-2.6.6/bin:/usr/local/rvm/gems/ruby-2.6.6@global/bin:/usr/local/rvm/rubies/ruby-2.6.6/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/rvm/bin:/root/bin:${PATH}"
+
 # Install Ruby
 RUN rvm install 2.6.6 \
  && rvm alias create 2.6 ruby-2.6.6 \
  && rvm use --default 2.6.6
 
 RUN gem install -N fpm-cookery
-