deps: update grpc dependencies to v1.68.0 (#3220)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [io.grpc:grpc-core](https://redirect.github.com/grpc/grpc-java) |
`1.66.0` -> `1.68.0` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/io.grpc:grpc-core/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/io.grpc:grpc-core/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/io.grpc:grpc-core/1.66.0/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/io.grpc:grpc-core/1.66.0/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
| [io.grpc:grpc-bom](https://redirect.github.com/grpc/grpc-java) |
`1.66.0` -> `1.68.0` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/io.grpc:grpc-bom/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/io.grpc:grpc-bom/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/io.grpc:grpc-bom/1.66.0/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/io.grpc:grpc-bom/1.66.0/1.68.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency
Dashboard for more information.

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about these
updates again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/googleapis/sdk-platform-java).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOC44MC4wIiwidXBkYXRlZEluVmVyIjoiMzguOTQuMyIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOltdfQ==-->

---------

Co-authored-by: Lawrence Qiu <[email protected]>

Author: renovate-bot

.cloudbuild/library_generation/library_generation.Dockerfile

@@ -34,7 +34,7 @@ SHELL [ "/bin/bash", "-c" ]
 
 ARG OWLBOT_CLI_COMMITTISH=ac84fa5c423a0069bbce3d2d869c9730c8fdf550
 ARG PROTOC_VERSION=25.5
-ARG GRPC_VERSION=1.66.0
+ARG GRPC_VERSION=1.68.0
 ENV HOME=/home
 ENV OS_ARCHITECTURE="linux-x86_64"
 

gapic-generator-java-pom-parent/pom.xml

@@ -26,7 +26,7 @@
     <!-- External dependencies, especially gRPC and Protobuf version, should be
         consistent across modules in this repository -->
     <javax.annotation-api.version>1.3.2</javax.annotation-api.version>
-    <grpc.version>1.66.0</grpc.version>
+    <grpc.version>1.68.0</grpc.version>
     <google.auth.version>1.27.0</google.auth.version>
     <google.http-client.version>1.45.0</google.http-client.version>
     <gson.version>2.11.0</gson.version>