Adding support to style attributes in SVG files

[RedShy]

I implemented the support for SVG with CSS styling elements simply by parsing the style attribute and inserting the key-value pairs as attributes of the element and then reusing the existing code. Close #404

I tested it using the SVG files downloadable from Ghostscript examples and it works! There are some with linear gradient not supported but the others seems to be okay.
I added some tests in test_svg.py to cover the new feature.

I also have added simple tests for the file transitions.py given that was the least covered with the aim of increase test coverage.

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

• 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

• The PR description or comment contains a picture of a cute animal (not mandatory but encouraged 😉)

[codecov]

Codecov Report

Merging #419 (3d7cf4d) into master (3b442f1) will increase coverage by 0.13%.
The diff coverage is 92.85%.

❗ Current head 3d7cf4d differs from pull request most recent head 12c92d1. Consider uploading reports for the commit 12c92d1 to get more accurate results

@@            Coverage Diff             @@
##           master     #419      +/-   ##
==========================================
+ Coverage   91.19%   91.32%   +0.13%     
==========================================
  Files          22       22              
  Lines        6347     6238     -109     
  Branches     1282     1253      -29     
==========================================
- Hits         5788     5697      -91     
+ Misses        315      305      -10     
+ Partials      244      236       -8     

Impacted Files	Coverage Δ
fpdf/svg.py	97.50% <92.85%> (-0.13%)	⬇️
fpdf/prefs.py	90.90% <0.00%> (-1.95%)	⬇️
fpdf/enums.py	98.91% <0.00%> (-0.29%)	⬇️
fpdf/drawing.py	93.13% <0.00%> (-0.26%)	⬇️
fpdf/fpdf.py	87.73% <0.00%> (-0.02%)	⬇️
fpdf/__init__.py	100.00% <0.00%> (ø)
fpdf/transitions.py	94.93% <0.00%> (+24.05%)	⬆️

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[Lucas-C]

Note that currently the GitHub Actions pipeline is failing because your code is not formatted with black:
https://pyfpdf.github.io/fpdf2/Development.html#code-auto-formatting

Just run black . in the repository root directory to fix this.

[Lucas-C]

@allcontributors please add @RedShy for code

[allcontributors]

@Lucas-C

I've put up a pull request to add @RedShy! 🎉

[Lucas-C]

This looks great!
Thank you for implementing this, and for adding unit tests!

There are few remaining things that would be great to add to this PR:

• a test checking that the correct order of priority is implemented between attributes from style & SVG attributes: check https://stackoverflow.com/a/36755226/636849
• a mention of this improvement & your name in an Added section in CHANGELOG.md: take inspiration from the previous entries 😊
• keeping the documentation up-to-date, and especially the page about SVG support & limitations: I think the part about style-based limitations could be removed

[Lucas-C]

Merging now, thank you for your contribution @RedShy!

[RedShy]

Thank you! it's very rewarding having someone that is supportive and reviews so fast on the other hand!

[Lucas-C]

Thanks 😊
I see it as part of the role of a FLOSS project maintainer.

I hope you liked making this first contribution to an open source project,
and that you will do many others!

[Lucas-C]

This feature has been included in the new v2.5.5 release!