Made the Parameter class no obsolete (#1644)

Author: alexeyzimarev

src/RestSharp/Parameter.cs

@@ -24,7 +24,6 @@ namespace RestSharp {
     /// <summary>
     /// Parameter container for REST requests
     /// </summary>
-    [Obsolete("Use Add[XXX]Parameter methods of IRestRequest instead of instantiating the Parameter class.")]
     public class Parameter : IEquatable<Parameter> {
         public Parameter(string name, object? value, ParameterType type, bool encode = true) {
             if (type != ParameterType.RequestBody)