Check name update in mergify

The check name was modified to tox and this commit updates the
mergify configuration.

Signed-off-by: Pragadeeswaran Sathyanarayanan <[email protected]>

Author: psathyan

.github/mergify.yml

@@ -6,7 +6,7 @@ pull_request_rules:
       - label!=work-in-progress
       - base=master
       - branch-protection-review-decision=approved
-      - check-success=tox (3.7)
+      - check-success=tox
     actions:
       merge:
         method: merge