Log Message:
py-lmfit: updated to 0.9.13

Version 0.9.13 Release Notes

New features:
Clearer warning message in fit reports when uncertainties should but cannot be \ 
estimated, including guesses of which Parameters to examine
SplitLorenztianModel and split_lorentzian function
HTML representations for Parameter, MinimizerResult, and Model so that they can \ 
be printed better with Jupyter
support parallelization for differential evolution

Bug fixes:
delay import of matplotlib (and so, the selection of its backend) as late as possible
fix for saving, loading, and reloading ModelResults
fix to leastsq to report the best-fit values, not the values tried last
fix synchronization of all parameter values on Model.guess()
improve deprecation warnings for outdated nan_policy keywords
fix for edge case in gformat()

Project managements:
using pre-commit framework to improve and enforce coding style
added code coverage report to github main page
updated docs, github templates, added several tests.
dropped support and testing for Python 3.4.