Update version to 8.0.0 for .NET 8 LTS branch

- Change package version from 1.1.0 to 8.0.0 to align with .NET version
- Update test project to target net8.0
- This is the maintenance branch for .NET 8 LTS support

Author: GmausDev

src/CompactifAI.Client/CompactifAI.Client.csproj

@@ -8,7 +8,7 @@
 
     <!-- NuGet Package Properties -->
     <PackageId>CompactifAI.Client</PackageId>
-    <Version>1.1.0</Version>
+    <Version>8.0.0</Version>
     <Authors>GmausDev</Authors>
     <Company>GmausDev</Company>
     <Description>A .NET client library for the CompactifAI API. Easily integrate AI chat completions, text completions, and audio transcription into your .NET applications.</Description>

tests/CompactifAI.Client.Tests/CompactifAI.Client.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net10.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>