Prepare 7.11.0 (#20130)

* Revert "prepare 7.10.0 release (#20128)"

This reverts commit 12dfe8fe74.

* update to 7.11.0-SNAPSHOT, update samples

* update docs

samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/.openapi-generator/VERSION

@@ -1 +1 @@
-7.10.0-SNAPSHOT
+7.11.0-SNAPSHOT

samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/README.md

@@ -6,7 +6,7 @@ This C# SDK is automatically generated by the [OpenAPI Generator](https://openap
 
 - API version: 1.0.0
 - SDK version: 1.0.0
-- Generator version: 7.10.0-SNAPSHOT
+- Generator version: 7.11.0-SNAPSHOT
 - Build package: org.openapitools.codegen.languages.CSharpClientCodegen
 
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