Screen for being on a release branch before doing the version bump test in CI build

.build.yml

@@ -98,15 +98,23 @@ tasks:
   - version_bump_test: |
       SECONDS=0
 
+      cd twitter_offline_engine/cmd
+
+      version=$(git branch --show-current | grep -Poh "(?<=^release-)\d+\.\d+\.\d+") || true
+      if [[ -z "$version" ]]
+      then
+          # Not on a release branch; just exit this task
+          exit
+      fi
+
       sudo apt install -y curl gnupg
-      sudo curl https://apt.playfulpachyderm.com/KEY.gpg | apt-key add -
+      curl https://apt.playfulpachyderm.com/KEY.gpg | sudo apt-key add -
       sudo echo "deb https://apt.playfulpachyderm.com/ ./" > /etc/apt/sources.list.d/offline_twitter.list
       sudo apt update
 
       sudo apt install -y offline-twitter-engine  # Latest released version
       which twitter  # Ensure that it got installed
 
-      cd twitter_offline_engine/cmd
       twitter create_profile outdated_profile
       cd outdated_profile