project: revert migrate renovate config

This reverts commit e86cd73675.

.github/renovate.json5

@@ -8,9 +8,7 @@
   ],
   schedule: ["before 8am on thursday"],
   branchPrefix: "renovate-",
-  dependencyDashboard: {
-    header: "View repository job log [here](https://app.renovatebot.com/dashboard#github/cmur2/dyndnsd).",
-  },
+  dependencyDashboardHeader: "View repository job log [here](https://app.renovatebot.com/dashboard#github/cmur2/dyndnsd).",
   separateMinorPatch: true,
   commitMessagePrefix: "project: ",
   commitMessageAction: "update",