Release Google.Cloud.Notebooks.V2 version 1.2.0 (#12894)

Changes in this release:

### New features

- Add IServiceCollection extension methods for client registration where an IServiceProvider is required. ([commit 022fab2](https://togithub.com/googleapis/google-cloud-dotnet/commit/022fab203f28fb9c608972af7f8b83f571ae5694))

apis/Google.Cloud.Notebooks.V2/Google.Cloud.Notebooks.V2/Google.Cloud.Notebooks.V2.csproj

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <Version>1.1.0</Version>
+    <Version>1.2.0</Version>
     <TargetFrameworks>netstandard2.0;net462</TargetFrameworks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <Description>Recommended Google client library to access the AI Platform Notebooks API (v2), which is used to manage notebook resources in Google Cloud.</Description>

apis/Google.Cloud.Notebooks.V2/docs/history.md

@@ -1,5 +1,11 @@
 # Version history
 
+## Version 1.2.0, released 2024-05-14
+
+### New features
+
+- Add IServiceCollection extension methods for client registration where an IServiceProvider is required. ([commit 022fab2](https://github.com/googleapis/google-cloud-dotnet/commit/022fab203f28fb9c608972af7f8b83f571ae5694))
+
 ## Version 1.1.0, released 2024-03-26
 
 ### New features

apis/apis.json

@@ -3394,7 +3394,7 @@
     },
     {
       "id": "Google.Cloud.Notebooks.V2",
-      "version": "1.1.0",
+      "version": "1.2.0",
       "type": "grpc",
       "productName": "Notebooks",
       "productUrl": "https://cloud.google.com/vertex-ai/docs/workbench/instances/introduction",