port generic Renovate options from gitea's renovate.json5 (#545)

Ports repo-agnostic options from gitea/gitea's `renovate.json5`:

- `default.json`: `minimumReleaseAge: "5 days"`, `configMigration: true`
- `go-deps.json`: `gomodUpdateImportPaths` postUpdateOption + immediate Go toolchain bumps (opt-in preset, no-op without `go.mod`)
- `npm-deps.json`: `pnpmDedupe` postUpdateOption (no-op for non-pnpm repos)

Reviewed-on: https://gitea.com/gitea/renovate-config/pulls/545
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

go-deps.json

@@ -4,12 +4,22 @@
     "enabled": true
   },
   "postUpdateOptions": [
-    "gomodTidy"
+    "gomodTidy",
+    "gomodUpdateImportPaths"
   ],
   "packageRules": [
     {
       "groupName": "Go dependencies",
       "matchManagers": ["gomod"]
+    },
+    {
+      "description": "Bump the Go toolchain version immediately",
+      "matchManagers": ["gomod"],
+      "matchDepNames": ["go"],
+      "matchDepTypes": ["golang"],
+      "rangeStrategy": "bump",
+      "schedule": ["at any time"],
+      "minimumReleaseAge": "0"
     }
   ]
 }