Auto merge of #3911 - Turbo87:renovate, r=locks

renovatebot: Enable `rust` manager, but only with dashboard approval

After this PR all pending Rust dependency updates should show up on #2689. They won't be opened automatically as PRs, but they should have a checkbox allowing us to half-manually create them.

This should give us a better overview of what dependency updates are pending, without hammering CI too much.

renovate.json → .github/renovate.json

@@ -16,7 +16,7 @@
         "reviewersSampleSize": 1
     },
     "rust": {
-        "enabled": false
+        "dependencyDashboardApproval": true
     },
     "postUpdateOptions": ["yarnDedupeFewer"],
     "packageRules": [{
@@ -25,5 +25,9 @@
     }, {
         "matchPackageNames": ["@percy/cli", "webpack"],
         "extends": ["schedule:weekly"]
+    }, {
+        "matchLanguages": ["rust"],
+        "matchUpdateTypes": ["lockFileMaintenance"],
+        "groupName": " Lock file maintenance (Rust)"
     }]
 }