remove aws credentials.signatureVersion in enableS3TransferAcceleration

Fix error: The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256.

See more: https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region

lib/plugins/aws/provider/awsProvider.js

@@ -328,8 +328,6 @@ class AwsProvider {
   enableS3TransferAcceleration(credentials) {
     this.serverless.cli.log('Using S3 Transfer Acceleration Endpoint...');
     credentials.useAccelerateEndpoint = true;  // eslint-disable-line no-param-reassign
-    credentials.signatureVersion = 'v2';  // eslint-disable-line no-param-reassign
-    // see https://github.com/aws/aws-sdk-js/issues/281
   }
 
   getRegion() {