reverted the [String: Any] for response headers instead of [String: String]

Author: mohammedDehairy

AdyenNetworking/APIClient/Errors.swift

@@ -21,7 +21,7 @@ public enum APIClientError: LocalizedError {
 public struct ParsingError: LocalizedError {
 
     /// HTTP Headers.
-    public let headers: [String: Any]
+    public let headers: [String: String]
 
     /// HTTP Status Code.
     public let statusCode: Int

AdyenNetworking/APIClient/HTTPResponse.swift

@@ -9,7 +9,7 @@ import Foundation
 public struct HTTPResponse<R: Response> {
 
     /// HTTP Headers.
-    public let headers: [String: Any]
+    public let headers: [String: String]
 
     /// HTTP Status Code.
     public let statusCode: Int

AdyenNetworking/Helpers/URLSessionHelpers.swift

@@ -11,12 +11,12 @@ internal struct URLSessionSuccess {
 
     internal let statusCode: Int
 
-    internal let headers: [String: Any]
+    internal let headers: [String: String]
 
     internal init(data: Data?, response: URLResponse?) throws {
         guard let data = data,
               let httpResponse = response as? HTTPURLResponse,
-              let headers = httpResponse.allHeaderFields as? [String: Any] else {
+              let headers = httpResponse.allHeaderFields as? [String: String] else {
                   throw APIClientError.invalidResponse
         }