generate v1.26 (#1122)

* update swagger

* remove unused models in converter

* remove netcore3.1 from testr

* bump ver

* fix convert

* remove some unused autorest property

* move some clz from autorest to client

* fix import

* no longer expose SendRequestRaw

* make file utils inner

* fix build

* c# 11

tests/KubernetesClient.Tests/KubernetesClient.Tests.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <IsPackable>false</IsPackable>
     <RootNamespace>k8s.Tests</RootNamespace>
-    <TargetFrameworks>netcoreapp3.1;net6.0;net7.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>