Fixing issue #1223: pdf.font_style now behaves like pdf.set_font

[smilerightnow]

Fixes #1223

Checklist:

• The GitHub pipeline is OK (green),
  meaning that both pylint (static code analyzer) and black (code formatter) are happy with the changes of this PR.

• A unit test is covering the code added / modified by this PR

• This PR is ready to be merged

• [N/A] In case of a new feature, docstrings have been added, with also some documentation in the docs/ folder

• A mention of the change is present in CHANGELOG.md

By submitting this pull request, I confirm that my contribution is made under the terms of the GNU LGPL 3.0 license.

[andersonhc]

Hi @smilerightnow
Pylint is failing on the file below

Run pylint fpdf test tutorial/tuto*.py
************* Module fpdf.fpdf
fpdf/fpdf.py:1946:0: C0303: Trailing whitespace (trailing-whitespace)```

[smilerightnow]

thanks @andersonhc for pointing it out, I removed the 4 spaces :)

[Lucas-C]

Hi @smilerightnow

Thank you for submitting this PR 🙂

I just took a look at it, and it seems that this does not implement the solution discussed in #1223:

• this PR currently introduces a ._font_style attribute, whereas I suggested an ._emphasis attribute
• this PR introduce new .font_style properties, but this was not required
• this PR does make the pre-existing emphasis propery and .underline .font_style depend on the new ._emphasis attribute, which is the main goal there

Could you pleasae re-read the original issue @smilerightnow in order to better understand the requirements?