Bug 1720386 - Add a regex for Thunderbird update-verify-next version …

…matching. r=taskgraph-reviewers,bhearsum

The update-verify-next test is new in Thunderbird 91. Since Thunderbird versions
do not include the esr suffix, a separate regex is needed.

Differential Revision: https://phabricator.services.mozilla.com/D119890

taskcluster/taskgraph/transforms/update_verify_config.py

@@ -35,6 +35,8 @@
     "esr": r"'^\d+\.\d+(\.\d+)?esr$'",
     # Previous esr versions, for update testing before we update users to esr91
     "esr91-next": r"'^(52|60|68|78)+\.\d+(\.\d+)?esr$'",
+    # Previous Thunderbird major versions. Same idea as esrXX-next, no esr suffix
+    "thunderbird91-next": r"'^78\.\d+(\.\d+)?$",
 }
 
 MAR_CHANNEL_ID_OVERRIDE_REGEXES = {