text: Title: zlma issue
  Body: My environment is:
  Pandas-TA version 0.3.14b (current)
  TA-Lib version 0.4.25 (current)
  MAC OS
  
  I'm not able to use the non-default `mamode` when calling `zlma`
  
  This works
  ```python
  pta_params = {'length': 10, 'mamode': 'ema', 'offset': 0}
  df.ta.zlma(**pta_params, append=True)
  ```
  
  This does not work
  ```python
  pta_params = {'length': 10, 'mamode': 'rma', 'offset': 0}
  df.ta.zlma(**pta_params, append=True)
  ```
  All ma-mode options other than ema fail with the error
  
  ```sh
  Exception has occurred: TypeError
  'module' object is not callable
    File "ta.lib.tst.py", line 57, in <module>
      df.ta.zlma(**pta_params, append=True)
  TypeError: 'module' object is not callable
  ```