fix(renovate): add package rule for disabling toolchain updates (#10961)

#### Description
- Added a rule to ignore updates to the go toolchain. According to
[this](https://github.com/renovatebot/renovate/blob/main/lib/modules/manager/gomod/update.ts#L51-L55),
the toolchain update is a `depType` in the `gomod` manager.

#### Link to tracking issue
Fixes #10932

renovate.json

@@ -64,6 +64,11 @@
         "matchManagers": ["gomod"],
         "matchPackagePrefixes": ["go.opentelemetry.io/build-tools"],
         "groupName": "All go.opentelemetry.io/build-tools packages"
+      },
+      {
+        "matchManagers": ["gomod"],
+        "matchDepTypes": ["toolchain"],
+        "enabled": false
       }
     ],
     "ignoreDeps": [