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

.github/workflows/draft.yaml

@@ -18,7 +18,6 @@ jobs:
       uses: actions/setup-dotnet@v3
       with:
         dotnet-version: |
-          3.1.x
           6.0.x
           7.0.x