Feature 1904 req args

[JohnHalleyGotway]

Expected Differences

Fixing a very minor copy/paste bug in Gen-Ens-Prod.

• Do these changes introduce new tools, command line arguments, or configuration file options? [No]
  
  If yes, please describe:
  

• Do these changes modify the structure of existing or add new output data types (e.g. statistic line types or NetCDF variables)? [No]
  
  If yes, please describe:
  

Pull Request Testing

• Describe testing already performed for these changes:
  
  Prior to the bugfix, it does not tell you that -out is required:

gen_ens_prod  -ens data/sample_fcst/2009123112/arw-*/*.grib -config data/config/EnsembleStatConfig_default
ERROR  : process_ensemble() -> 0 of 6 (0) fields found for "APCP/A03" does not meet the threshold specified by "ens.ens_thresh" (1) in the configuration file.

After the bugfix, it does:

gen_ens_prod -ens data/sample_fcst/2009123112/arw-*/*.grib -config data/config/EnsembleStatConfig_default 
ERROR  : process_command_line() -> the output file must be set using the "-out" option.

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  
  No additional testing needed. Just review the one-line code change.

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes or No]
  None needed.

• Do these changes include sufficient testing updates? [No]
  None needed.

• Will this PR result in changes to the test suite? [No]
  
  If yes, describe the new output and/or changes to the existing output:
  

• Please complete this pull request review by [Monday 3/7].
  

Pull Request Checklist

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[jprestop]

I have reviewed this one line change and the new bugfix output. I approve this pull request.