Bump Semantic Kernel packages to 1.71.0

Update Microsoft.SemanticKernel and Microsoft.SemanticKernel.Abstractions from 1.67.1 to 1.71.0 in Directory.Packages.props to pick up upstream fixes and improvements. No other package versions were changed.

Author: enisn

Directory.Packages.props

@@ -89,8 +89,8 @@
     <PackageVersion Include="Microsoft.EntityFrameworkCore.Sqlite" Version="10.0.2" />
     <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="10.0.2" />
     <PackageVersion Include="Microsoft.EntityFrameworkCore.Tools" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.SemanticKernel" Version="1.67.1" />
-    <PackageVersion Include="Microsoft.SemanticKernel.Abstractions" Version="1.67.1" />
+    <PackageVersion Include="Microsoft.SemanticKernel" Version="1.71.0" />
+    <PackageVersion Include="Microsoft.SemanticKernel.Abstractions" Version="1.71.0" />
     <PackageVersion Include="Microsoft.Extensions.Caching.Hybrid" Version="9.9.0" />
     <PackageVersion Include="Microsoft.Extensions.Caching.Memory" Version="10.0.2" />
     <PackageVersion Include="Microsoft.Extensions.Caching.StackExchangeRedis" Version="10.0.2" />