[12.0] Merge shopinvader invoice + invoice download

[lmignon]

forward port of #407

[codecov-io]

Codecov Report

Merging #487 into 12.0 will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             12.0     #487      +/-   ##
==========================================
- Coverage   91.58%   91.57%   -0.02%     
==========================================
  Files         111      111              
  Lines        3127     3120       -7     
==========================================
- Hits         2864     2857       -7     
  Misses        263      263

Impacted Files	Coverage Δ
shopinvader_invoice/services/invoice.py	96.96% <100%> (-0.54%)	⬇️
shopinvader/services/invoice.py	81.66% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 194113a...2d7ae2e. Read the comment docs.

[lmignon]

/ocabot merge patch

[shopinvader-git-bot]

What a great day to merge this nice PR. Let's do it!
Prepared branch 12.0-ocabot-merge-pr-487-by-lmignon-bump-patch, awaiting test results.

[shopinvader-git-bot]

Congratulations, your PR was merged at c94df90. Thanks a lot for contributing to shopinvader. ❤️