Upgrade to .NET 6 (#22)

Author: emilklasson

src/Insurello.RabbitMqClient/Insurello.RabbitMqClient.fsproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <PackageId>Insurello.RabbitMqClient</PackageId>
     <Authors>Insurello</Authors>
     <Company>Insurello</Company>