upgrade: upgrade .net version

Author: Memoyu

Diff for: build/releasenotes.props

@@ -1,8 +1,7 @@
 <Project>
 	<PropertyGroup>
 		<EasyCachingBaseTestPackageNotes>
-			1. assign fixed cacheNulls value.
-			2. update EasyCaching.Core version to 1.9.2
+			1. update EasyCaching.Core version to 1.9.4
 		</EasyCachingBaseTestPackageNotes>
 	</PropertyGroup>
 </Project>

Diff for: build/version.props

@@ -1,5 +1,5 @@
 <Project>
 	<PropertyGroup>
-		<EasyCachingBaseTestPackageVersion>1.9.3</EasyCachingBaseTestPackageVersion>
+		<EasyCachingBaseTestPackageVersion>1.9.4</EasyCachingBaseTestPackageVersion>
 	</PropertyGroup>
 </Project>

Diff for: src/EasyCaching.BaseTest/EasyCaching.BaseTest.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFramework>net6.0</TargetFramework>
+		<TargetFramework>net8.0</TargetFramework>
 		<ImplicitUsings>enable</ImplicitUsings>
 		<IsPackable>true</IsPackable>
 	</PropertyGroup>
@@ -11,7 +11,7 @@
 		<PackageReference Include="FakeItEasy" Version="7.3.1" />
 		<PackageReference Include="MemoryPack" Version="1.9.13" />
 		<PackageReference Include="protobuf-net" Version="3.2.16" />
-		<PackageReference Include="xunit" Version="2.4.2" />
+		<PackageReference Include="xunit" Version="2.9.2" />
 	</ItemGroup>
 
 	<ItemGroup>