fix: replace gpg keyserver import for rvm (#585)

Author: ingride

Dockerfile

@@ -228,7 +228,7 @@ RUN adduser --system --disabled-password --uid 2500 --quiet buildbot --home /opt
 
 ## TODO: Consider switching to rbenv or asdf-vm
 USER buildbot
-RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB && \
+RUN curl -sSL https://rvm.io/mpapis.asc | gpg --import - && curl -sSL https://rvm.io/pkuczynski.asc | gpg2 --import && \
     curl -sL https://get.rvm.io | bash -s stable --with-gems="bundler" --autolibs=read-fail
 
 ENV PATH /usr/local/rvm/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin