mikropml 1.4.0

• Extra arguments given to run_ml() are now forwarded to caret::train() (#304, @kelly-sovacool).
  • Users can now pass any model-specific arguments (e.g. weights) to caret::train(), allowing greater flexibility.
• Improved tests (#298, #300, #303 #kelly-sovacool)
• Minor documentation improvements.

Full Changelog: v1.3.0...v1.4.0