Downgrade the version xUnit

Turns out that FsCheck doesn't work yet with xUnit.v3 3.0.0

Author: TolikPylypchuk

SharpHook.Tests/SharpHook.Tests.csproj

@@ -20,7 +20,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="xunit.v3" Version="3.0.0" />
+    <PackageReference Include="xunit.v3" Version="2.0.3" />
   </ItemGroup>
 
   <ItemGroup>