Have Renovate check main and next (fka refactor) branch.

cr1901 · cr1901 · commit 201dde56fe2a · 2024-03-07T00:35:18.000-05:00
diff --git a/.github/renovate.json b/.github/renovate.json
@@ -5,5 +5,6 @@
     "schedule:weekly",
     "group:all",
     ":approveMajorUpdates"
-  ]
+  ],
+  "baseBranches": ["main", "next"]
 }
