ci(github): merge with squash in mergify.yml

https://docs.mergify.com/actions/merge/#options

Signed-off-by: Mark <remarkablemark@users.noreply.github.com>

Author: remarkablemark

.github/mergify.yml

@@ -8,4 +8,4 @@ pull_request_rules:
       - 'title~=^build\(deps-dev\): bump '
     actions:
       merge:
-        method: merge
+        method: squash