fix(core): update TargetFramework to net10.0 to match NuGet package requirements (#95)

BlazorMVU.Core targeted net9.0 but referenced Microsoft.AspNetCore.Components.Web
10.0.3 and Microsoft.JSInterop 10.0.3 which only support net10.0, causing CI to
fail with NU1202 restore errors. Aligns with Demo and Tests projects already on net10.0.

Author: phmatray

src/BlazorMVU.Core/BlazorMVU.Core.csproj

@@ -1,10 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk.Razor">
 
   <PropertyGroup>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
-    <LangVersion>12</LangVersion>
+    <LangVersion>13</LangVersion>
     <RootNamespace>BlazorMVU</RootNamespace>
 
     <!-- NuGet Package Properties -->