replace v6 with experimental v7 code

src/MpvNet.Windows/StringPair.cs

@@ -0,0 +1,13 @@
+namespace MpvNet.Windows;
+
+public class StringPair
+{
+    public string Name { get; set; }
+    public string Value { get; set; }
+
+    public StringPair(string name, string value)
+    {
+        Name = name;
+        Value = value;
+    }
+}