Fixed some version dependent parts

Author: martindevans

LLama/Native/NativeApi.cs

@@ -40,13 +40,15 @@ private static IntPtr TryLoadLibrary()
         {
             if (Environment.OSVersion.Platform == PlatformID.Win32NT)
             {
+#if NET6_0_OR_GREATER
                 var cuda = LoadLibrary("win-cuda12/libllama.dll");
                 if (cuda != IntPtr.Zero)
                     return cuda;
 
                 cuda = LoadLibrary("win-cuda11/libllama.dll");
                 if (cuda != IntPtr.Zero)
                     return cuda;
+#endif
 
 #if NET8_0_OR_GREATER
                 if (System.Runtime.Intrinsics.X86.Avx512.IsSupported)
@@ -59,8 +61,8 @@ private static IntPtr TryLoadLibrary()
 
                 if (System.Runtime.Intrinsics.X86.Avx.IsSupported)
                     return LoadLibrary("win-avx/libllama.dll");
-            }
 #endif
+            }
 
             return IntPtr.Zero;
         }