fix: two Swift compile warnings (#517)

Author: jbelkins

Sources/ClientRuntime/Networking/SdkError.swift

@@ -24,7 +24,7 @@ extension SdkError: WaiterTypedError {
         case .service(let error, _):
             return (error as? WaiterTypedError)?.waiterErrorType
         case .client(let error, _):
-            return (error as? WaiterTypedError)?.waiterErrorType
+            return error.waiterErrorType
         case .unknown(let error):
             return (error as? WaiterTypedError)?.waiterErrorType
         }

Sources/ClientRuntime/Serialization/Encoder/XMLEncoder+Extensions.swift

@@ -8,7 +8,7 @@ import XMLCoder
 
 public typealias XMLEncoder = XMLCoder.XMLEncoder
 extension XMLEncoder: RequestEncoder {
-    open func encode<T>(_ value: T) throws -> Data where T: Encodable {
+    public func encode<T>(_ value: T) throws -> Data where T: Encodable {
         return try encode(value, withRootKey: nil, rootAttributes: nil, header: nil)
     }
 }