Increase version to 2.23.1 (for v2.23.x branch) (#499)

Author: jtattermusch

build/version.props

@@ -2,13 +2,13 @@
   <PropertyGroup>
 
     <!-- package version of grpc-dotnet -->
-    <GrpcDotnetVersion>2.23.0</GrpcDotnetVersion>
+    <GrpcDotnetVersion>2.23.1</GrpcDotnetVersion>
 
     <!-- assembly version of grpc-dotnet -->
     <GrpcDotnetAssemblyVersion>2.0.0.0</GrpcDotnetAssemblyVersion>
 
     <!-- file version of all grpc-dotnet -->
-    <GrpcDotnetAssemblyFileVersion>2.23.0.0</GrpcDotnetAssemblyFileVersion>
+    <GrpcDotnetAssemblyFileVersion>2.23.1.0</GrpcDotnetAssemblyFileVersion>
 
   </PropertyGroup>
 </Project>