Add support for python 3.10

[rainman110]

We also should reevaluate, which python versions we still want to support. Currently, we support the four versions

• 3.6
• 3.7
• 3.8
• 3.9

Adding a fifth version will put more pressure on the CI system, so dropping one (3.6?) might be beneficial.

[joergbrech]

I agree. Let's build for a maximum of four Python versions. Which ones should it be? We could pick the most recent ones, e.g. 3.8, 3.9, 3.10, 3.11.

[rainman110]

I think we need to figure out, what the tigl users are actually using.

[rainman110]

A quick check on the download numbers show, that python 3.9 and python 3.7 are the most downloaded. Dropping 3.7 could hence be an issue.

[rainman110]

By the way, python 3.6 is and of life and python 3.7 will be soon.

[joergbrech]

Ok, so I suppose a good policy would be to kick out end-of-life Python versions.

That would still leave us with currently five Python versions that must be supported. 3.7 will reach end-of-life soon, but 3.12 is just around the corner...