Bump merge from 1.2.0 to 2.1.1 in /automation/taskcluster/graph

Bumps [merge](https://github.com/yeikos/js.merge) from 1.2.0 to 2.1.1.
- [Release notes](https://github.com/yeikos/js.merge/releases)
- [Commits](swordev/merge@v1.2.0...v2.1.1)

Signed-off-by: dependabot[bot] <support@github.com>

automation/taskcluster/graph/package.json

@@ -16,7 +16,7 @@
     "flatmap": "0.0.3",
     "intersect": "^1.0.1",
     "js-yaml": "^3.6.1",
-    "merge": "^1.2.0",
+    "merge": "^2.1.1",
     "minimist": "^1.2.0",
     "slugid": "^1.1.0",
     "taskcluster-client": "^22.0.0"