Multiple CI and README.md Improvements (backport #324)

[mergify]

This PR makes many improvements to the CI and README.md.
The CI builds are a bit faster now and are run for v5.2, v5.3, and v5.4 of ESP-IDF.
I also removed CI compatibility and mentions of ESP-IDF v4.4, as it's been declared EOL by Espressif for a while now.

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This is part 3 of 4 in a stack made with GitButler:

•  4  Add Support for ESP-IDF v5.5 #325
•  3  Multiple CI and README.md Improvements #324 👈
•  2  Fix rolling builds #323
•  1  Remove atomic patch #329

Changes specific to this PR: c9c54a8

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This is an automatic backport of pull request #324 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of d749ff1 has failed:

On branch mergify/bp/humble/pr-324
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit d749ff1.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .github/workflows/ci.yml
	both modified:   .github/workflows/nightly.yml
	both modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[Amronos]

Let's backport #341 to humble instead.