Update pull-requests.json (#4949)

Author: ev1yehor

.buildkite/pull-requests.json

@@ -21,7 +21,7 @@
             "pipelineSlug": "elastic-agent-package",
             "allow_org_users": true,
             "allowed_repo_permissions": ["admin", "write"],
-            "allowed_list": [],
+            "allowed_list": ["dependabot[bot]", "mergify[bot]"],
             "set_commit_status": false,
             "build_on_commit": false,
             "build_on_comment": true,
@@ -37,7 +37,7 @@
             "pipelineSlug": "elastic-agent-binary-dra",
             "allow_org_users": true,
             "allowed_repo_permissions": ["admin", "write"],
-            "allowed_list": [],
+            "allowed_list": ["dependabot[bot]", "mergify[bot]"],
             "set_commit_status": false,
             "build_on_commit": false,
             "build_on_comment": true,