v1.4.3

• Fix to make it None when SQLAlchemy's URI username and password are empty strings.
  If you do not specify aws_access_key_id and aws_secret_access_key in SQLAlchemy using the instance profile or boto3 configuration file, the connection string is as follows:

  awsathena+rest://:@athena.{region_name}.amazonaws.com:443/{schema_name}?s3_staging_dir={s3_staging_dir}&...
  

  Thanks @leahein. (/issues/54)
• Fix double escaping of percent character in SQLAlchemy.
  Thanks @mister-average. (/issues/56)