[chore] skip v1.68.0 of grpc dep (open-telemetry#36577)

Trying to add this to avoid getting notified until the next release is
available.

Related to
open-telemetry#36548

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

renovate.json

@@ -108,6 +108,10 @@
           "https://github.com/open-telemetry/opentelemetry-go-contrib"
         ],
         "groupName": "All opentelemetry-go-contrib packages"
+      },
+      {
+        "matchPackageNames": ["google.golang.org/grpc"],
+        "allowedVersions": "!/v1.68.0$/"
       }
     ],
     "ignoreDeps": [