CI: Fetch RVM gpg key on osx

CI/install-dependencies-osx.sh

@@ -7,6 +7,7 @@ set -v
 git fetch --unshallow
 
 # Fix ruby issue on OSX https://github.com/travis-ci/travis-ci/issues/6307
+gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
 rvm get stable
 
 # Leave obs-studio folder