Minor fixes

[andrea-pasquale]

In this PR I've fixed a few minor problems raised in #94 and #80.
In particular:

• the plotting methods have been splitted into files as already described in Refactor plotting methods #94
• I've downgraded the logs regarding folder creation from warnings to info, so they will not appear anymore in
  the output file. It is possible to change the log level using the environment variable QIBOCAL_LOG_LEVEL.
• now the logs are colored, you can see the colors using for example less -R output_file

I've also updated the pyproject.toml by adding a lmfit dependency since it is no longer a qibolab dependency and it is needed for all the fitting methods that we have in qibocal.
Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[codecov]

Codecov Report

Merging #122 (3a57734) into main (86a4894) will decrease coverage by 5.54%.
The diff coverage is 16.48%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #122      +/-   ##
==========================================
- Coverage   24.41%   18.86%   -5.55%     
==========================================
  Files          12       19       +7     
  Lines         684     1044     +360     
==========================================
+ Hits          167      197      +30     
- Misses        517      847     +330     

Flag	Coverage Δ
unittests	18.86% <16.48%> (-5.55%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/qibocal/config.py	37.50% <10.00%> (-18.75%)	⬇️
src/qibocal/plots/spectroscopies.py	10.81% <10.81%> (ø)
src/qibocal/plots/rabi.py	12.65% <12.65%> (ø)
src/qibocal/plots/calibrate_qubit_states.py	12.90% <12.90%> (ø)
src/qibocal/plots/allXY.py	15.38% <15.38%> (ø)
src/qibocal/plots/flipping.py	24.00% <24.00%> (ø)
src/qibocal/plots/ramsey.py	24.00% <24.00%> (ø)
src/qibocal/plots/t1.py	25.00% <25.00%> (ø)
src/qibocal/plots/__init__.py	100.00% <100.00%> (ø)
src/qibocal/plots/heatmaps.py	0.00% <0.00%> (-17.65%)	⬇️
... and 1 more

[andrea-pasquale]

@scarrazza coverage is decreasing because of the logger, shall include some tests now?
I think that as we include tests in the future for the calibration routines we should be able to cover also this part of the code.
Let me know.

[andrea-pasquale]

@scarrazza as discussed yersterday I will merge this now. Tests are not passing only because of coverage we will fix this in another PR.