build-rpms: Replace v4.20 jobs with v4.22

Author: anoopcs9

jobs/nightly-samba-builds.yml

@@ -9,7 +9,7 @@
       - 'aarch64'
     samba_branch:
       - 'master'
-      - 'v4-20-test'
+      - 'v4-22-test'
       - 'v4-21-test'
     jobs:
       - 'samba_build-rpms-{os_version}-{samba_branch}-{os_arch}'