Fix Release issue (#153)

* fix: rename override -> override_existing

"override" is the incorrect variable name when using UpsertUsersAsync api. Instead "override_existing" should be used

* fix: Add version

Author: sinapy

src/stream-net.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup Label="Configuration">
     <DefineConstants>TRACE;DEBUG;NETCORE</DefineConstants>
   </PropertyGroup>
@@ -8,7 +8,7 @@
   <PropertyGroup>
     <PackageId>stream-net</PackageId>
     <Title>.NET Client for Stream Feeds</Title>
-    <Version>6.10.1</Version>
+    <Version>6.12.0</Version>
     <Company>Stream.io</Company>
     <Authors>GetStream.io</Authors>
     <Copyright>© $([System.DateTime]::UtcNow.ToString(yyyy)) Stream.io</Copyright>