Enhance framework compatibility

LLama/Common/FixedSizeQueue.cs

@@ -43,7 +43,7 @@ public FixedSizeQueue(int size)
         /// <param name="data"></param>
         public FixedSizeQueue(int size, IEnumerable<T> data)
         {
-#if !NETSTANDARD2_0 
+#if NET6_0_OR_GREATER
             // Try to check the size without enumerating the entire IEnumerable. This may not be able to get the count,
             // in which case we'll have to check later
             if (data.TryGetNonEnumeratedCount(out var dataCount) && dataCount > size)

LLama/Extensions/DictionaryExtensions.cs

@@ -9,6 +9,8 @@ public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TK
         {
             return GetValueOrDefaultImpl(dictionary, key, defaultValue);
         }
+#elif !NET6_0_OR_GREATER && !NETSTANDARD2_1_OR_GREATER
+#error Target framework not supported!
 #endif
 
         internal static TValue GetValueOrDefaultImpl<TKey, TValue>(IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, TValue defaultValue)

LLama/Extensions/EncodingExtensions.cs

@@ -15,6 +15,8 @@ public static int GetCharCount(this Encoding encoding, ReadOnlySpan<byte> bytes)
     {
         return GetCharCountImpl(encoding, bytes);
     }
+#elif !NET6_0_OR_GREATER && !NETSTANDARD2_1_OR_GREATER
+#error Target framework not supported!
 #endif
 
     internal static int GetCharsImpl(Encoding encoding, ReadOnlySpan<byte> bytes, Span<char> output)

LLama/Extensions/IEnumerableExtensions.cs

@@ -10,6 +10,8 @@ public static IEnumerable<T> TakeLast<T>(this IEnumerable<T> source, int count)
         {
             return TakeLastImpl(source, count);
         }
+#elif !NET6_0_OR_GREATER && !NETSTANDARD2_1_OR_GREATER
+#error Target framework not supported!
 #endif
 
         internal static IEnumerable<T> TakeLastImpl<T>(IEnumerable<T> source, int count)

LLama/Extensions/KeyValuePairExtensions.cs

@@ -19,5 +19,7 @@ public static void Deconstruct<TKey, TValue>(this System.Collections.Generic.Key
         first = pair.Key;
         second = pair.Value;
     }
+#elif !NET6_0_OR_GREATER && !NETSTANDARD2_1_OR_GREATER
+#error Target framework not supported!
 #endif
 }

LLama/Extensions/ListExtensions.cs

@@ -5,7 +5,7 @@ namespace LLama.Extensions
 {
     internal static class ListExtensions
     {
-#if NETSTANDARD2_0
+#if !NET6_0_OR_GREATER
         public static void EnsureCapacity<T>(this List<T> list, int capacity)
         {
             if (list.Capacity < capacity)