Add sanity check for 'brz' command

Added sanity check for 'brz' command in workflow.

Author: Flamefire

.github/workflows/synchronize-launchpad.yml

@@ -33,6 +33,10 @@ jobs:
           sed -i '1 i from breezy import controldir' $fastimport_dir/branch_updater.py
           sed -i 's/helpers.binary_stream(sys.stdin)/sys.stdin.buffer/' $fastimport_dir/cmds.py
 
+          # Sanity check
+          which brz
+          cat $(which brz)
+          brz --help
 
       - uses: actions/checkout@v4
         with: