Ensure renovate runs go mod tidy after updates (#163)

Author: FollowTheProcess

.github/renovate.json

@@ -1,26 +1,6 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
-  "extends": [
-    "config:recommended"
-  ],
-  "labels": [
-    "dependencies"
-  ],
-  "packageRules": [
-    {
-      "automerge": true,
-      "matchUpdateTypes": [
-        "minor",
-        "patch",
-        "pin",
-        "digest"
-      ]
-    },
-    {
-      "automerge": true,
-      "matchDepTypes": [
-        "devDependencies"
-      ]
-    }
-  ]
-}
+  "extends": ["config:recommended"],
+  "labels": ["dependencies"],
+  "postUpdateOptions": ["gomodTidy"]
+}