Bump io.grpc:grpc-stub from 1.56.1 to 1.68.0

Bumps [io.grpc:grpc-stub](https://github.com/grpc/grpc-java) from 1.56.1 to 1.68.0.
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/commits)

---
updated-dependencies:
- dependency-name: io.grpc:grpc-stub
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

appsignals-tests/images/grpc/grpc-base/build.gradle.kts

@@ -27,7 +27,7 @@ dependencies {
 
   compileOnly("io.grpc:grpc-api:1.56.1")
   compileOnly("io.grpc:grpc-protobuf:1.56.1")
-  compileOnly("io.grpc:grpc-stub:1.56.1")
+  compileOnly("io.grpc:grpc-stub:1.68.0")
 }
 
 protobuf {

appsignals-tests/images/grpc/grpc-client/build.gradle.kts

@@ -30,7 +30,7 @@ dependencies {
 
   implementation("io.grpc:grpc-api:1.56.1")
   implementation("io.grpc:grpc-protobuf:1.56.1")
-  implementation("io.grpc:grpc-stub:1.56.1")
+  implementation("io.grpc:grpc-stub:1.68.0")
 
   runtimeOnly("io.grpc:grpc-netty-shaded")
 }

appsignals-tests/images/grpc/grpc-server/build.gradle.kts

@@ -29,7 +29,7 @@ dependencies {
 
   implementation("io.grpc:grpc-api:1.56.1")
   implementation("io.grpc:grpc-protobuf:1.56.1")
-  implementation("io.grpc:grpc-stub:1.56.1")
+  implementation("io.grpc:grpc-stub:1.68.0")
 
   runtimeOnly("io.grpc:grpc-netty-shaded")
   testImplementation(platform("org.junit:junit-bom:5.9.1"))