Improve coverage badge to be fully automatic

[astariul]

🧐 Context

The existing coverage badge is annoying to deal with : we often forget to run the command to update the coverage badge before pushing, leading to failing tests on the PR, despite the tests passing locally.

This is because the coverage badge is not truly automatic : the github action simply check if the current badge is up-to-date.

🔍️ Description

This PR moves the coverage badge to an external github Gist.

The github actions changes as well :

• On PR, after running the tests, we upload a message in the PR with the coverage results.
• Whenever something is pushed to the main branch, we run the tests and upload the freshly created coverage badge to the external github gist, effectively keeping the coverage badge automatically up-to-date.

✅ How this was tested ?

Tested on a dummy repo.

🌱 Checklist

• Perform self-review of my own code
• Comment the code, particularly in hard-to-understand areas
• Update the documentation accordingly to the new code
• Lint / format the code
• Update existing tests / Add new tests
• Tests are passing locally

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
kebbie
cmd.py	65	16	75%	179–207
emulator.py	448	308	31%	323–325, 327, 352–353, 355–356, 358–359, 361–362, 364–365, 367–368, 370–371, 373–374, 381, 387–401, 428–440, 478–496, 509–513, 522–578, 591–594, 605–617, 625–627, 638–658, 666, 678–682, 691–716, 728–735, 757–787, 803, 823–842, 854–861, 880–896, 905, 918–935, 944, 958–976, 985, 999–1013, 1022, 1036–1047, 1056, 1069–1081, 1090, 1103–1133, 1142, 1155–1168, 1181–1191, 1204–1218
TOTAL	1325	324	76%

Tests	Skipped	Failures	Errors	Time
341	0 💤	0 ❌	0 🔥	2.234s ⏱️

[QADavidCalvo]

Great! Thanks!