fix: Code consistency

Author: linkdotnet

src/LinkDotNet.StringBuilder/ValueStringBuilder.Append.cs

@@ -144,7 +144,7 @@ public void AppendLine(scoped ReadOnlySpan<char> str)
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public Span<char> AppendSpan(int length)
     {
-        int origPos = bufferPosition;
+        var origPos = bufferPosition;
         if (origPos > buffer.Length - length)
         {
             Grow(length);