Update copyright year to 2026 in project file

The copyright notice in ACadSharp.csproj was changed from 2024 to 2026 to reflect the current year. No other modifications were made.

Author: DomCR

src/ACadSharp/ACadSharp.csproj

@@ -9,7 +9,7 @@
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<RepositoryType>git</RepositoryType>
 		<PackageProjectUrl>https://github.com/DomCR/ACadSharp</PackageProjectUrl>
-		<Copyright>Copyright (c) 2024 Albert Domenech</Copyright>
+		<Copyright>Copyright (c) 2026 Albert Domenech</Copyright>
 		<Description>C# library to read/write cad files like dxf/dwg.</Description>
 		<GeneratePackageOnBuild Condition="'$(Configuration)' == 'Release'">True</GeneratePackageOnBuild>
 	</PropertyGroup>