deps: use protobuf 4.33.0, skip generation

Author: diegomarquezp

.github/workflows/hermetic_library_generation.yaml

@@ -15,7 +15,7 @@
 # downstream client libraries before they are released.
 name: Hermetic library generation upon generation config change through pull requests
 on:
-  pull_request:
+  #pull_request:
 
 env:
   REPO_FULL_NAME: ${{ github.event.pull_request.head.repo.full_name }}

pom.xml

@@ -58,6 +58,13 @@
 
   <dependencyManagement>
     <dependencies>
+      <dependency>
+        <groupId>com.google.protobuf</groupId>
+        <artifactId>protobuf-bom</artifactId>
+        <version>4.33.0</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-admin-instance-v1</artifactId>