deps: update grpc dependencies to v1.67.1 (#3258)

In https://github.com/grpc/grpc-java/releases/tag/v1.67.1, release note
states: "There was no 1.67.0 release. There was a problem making the
release and it went to Maven Central as 1.68.0 instead. This is a
version-corrected release." and
[#11553](grpc/grpc-java#11553) is included in
change list.

1.68.0 in maven central was meant to be 1.67.0, and 1.67.1 is the next
release after 1.68.0 (1.67.0)

.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=1.68.0
+ARG GRPC_VERSION=1.67.1
 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>1.68.0</grpc.version>
+    <grpc.version>1.67.1</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>