Fix CI, add Python 3.10

[johnnynunez]

• Python 3.6 & 3.7 deleted
• Python 3.10 & 3.11 added
• Flann is required
• Maintain macOS 11 only.
• Pybind11 compatible with Python 3.11

[sarlinpe]

Thanks for looking into this. I'm getting too many notifications so muting this PR for now - give us a heads up once it is ready for a full review.

[johnnynunez]

Thanks for looking into this. I'm getting too many notifications so muting this PR for now - give us a heads up once it is ready for a full review.

oh sorry so much, I didn't know that!

[johnnynunez]

@skydes First of all, apologies for the commits and notifications. It's difficult to work only with act.
For my part it work done, I think. I hope it will be the final one.

[johnnynunez]

@skydes How is it going?

[mihaidusmanu]

Looks good to me overall. Let's wait for Paul to take a look when he has a moment too. We will merge some other PRs that were stuck due to broken CI and then bump up version to 0.5 too.

[sarlinpe]

Let's delay the pybind upgrade because we'd need to simultaneously upgrade it in pyceres and pixsfm as well. This forces us to push back Python 3.11 support (though I don't think this is a big deal for now).