chore(renovate) group tracing packages by themselves

Follows up #1502

Putting the `tracing` packages into their own group to allow them to be
updated indepedently from the other packages which are generally more able
to be updated.

As it stands today, we are constrained in our ability to update the
`tracing` packages.

This should make it possible for them to be updated on-demand via the
Renovate Dependency Dashboard, if we choose to do so, and otherwise de-group
them from the other cargo updates.

renovate.json5

@@ -74,6 +74,20 @@
       "groupSlug": "all-non-major-gte-1.0",
       "automerge": true,
     },
+    // We're currently constrained in our ability to update the `tracing`
+    // packages to the latest versions because of our usage.  This should put
+    // those pacakges into their own group and away from other dep updates.
+    {
+      "matchManagers": [
+        "cargo"
+      ],
+      "matchPackagePatterns": [
+        "^tracing"
+      ],
+      "groupName": "cargo tracing packages",
+      "groupSlug": "cargo-tracing-packages",
+      "dependencyDashboardApproval": true
+    },
     {
       "matchPaths": [
         "docs/package.json"