Update grpc-netty, grpc-protobuf, grpc-stub to 1.68.0 (#1739)

Author: scala-steward

project/Dependencies.scala

@@ -4,7 +4,7 @@ import Keys._
 
 object Dependencies {
   object versions {
-    val grpc                 = "1.66.0"
+    val grpc                 = "1.68.0"
     val protobuf             = "4.26.0"
     val silencer             = "1.7.17"
     val collectionCompat     = "2.12.0"