fix: upgrade io.grpc:grpc-stub from 1.67.1 to 1.68.0

Snyk has created this PR to upgrade io.grpc:grpc-stub from 1.67.1 to 1.68.0.

See this package in maven:
io.grpc:grpc-stub

See this project in Snyk:
https://app.snyk.io/org/pantheon.tech/project/0115c39a-4f78-4555-8c38-8b5c512ef1d9?utm_source=github&utm_medium=referral&page=upgrade-pr

lighty-modules/lighty-gnmi/lighty-gnmi-proto/pom.xml

@@ -23,7 +23,7 @@
 
     <properties>
         <protobuf.version>3.25.5</protobuf.version>
-        <grpc.version>1.67.1</grpc.version>
+        <grpc.version>1.68.0</grpc.version>
     </properties>
 
     <dependencies>