title: inserting enum types to aurora postgres using boto3
body: <p>I have a schema which has a string and and enum that I am trying to write to using boto3.  I create a sql, specify parameters and run execute_statement. Easy enough for strings and dates:</p>
  
  <pre><code>    sql = """
            insert into scrape_results(lname,fname, dob) values (:lname, :fname, :dob)
            """              
      param1 = {'name':'lname', 'value':{'stringValue': 'xx'}}
      param3 = {'name':'dob', 'typeHint': 'DATE', 'value':{'stringValue': '1970-01-01'}}
      param_set = [param1, param2]     
      response = rds_data.execute_statement(
          resourceArn = cluster_arn, 
          secretArn = secret_arn, 
          database = 'db', 
          sql = sql,
          parameters = param_set)
  </code></pre>
  
  <p>The 3rd field I have is an enum. I do not follow how to insert an enum. There is no typeHint for enum, and boto does not accept a stringValue. I tried this: (court_type is the enum)</p>
  
  <pre><code>param3 = {'name':'court',  'value':{'stringValue': 'court'}}
  An error occurred (BadRequestException) when calling the ExecuteStatement operation: 
  ERROR: operator does not exist: court_type = character varying
  
  Hint: No operator matches the given name and argument type(s). 
  You might need to add explicit type casts
  </code></pre>