Fix Read the Docs build with modern setuptools

[behackl]

Summary

• replace the removed pkg_resources API in the Sphinx configuration
• read the installed ManimPango version through importlib.metadata

Read the Docs currently upgrades setuptools to 83, where pkg_resources is no longer available. This caused the configuration phase of build 33903390 to fail.

Testing

• built the package in a fresh Python 3.11 environment with setuptools 83.0.0
• successfully built the HTML documentation with Sphinx 9.0.4

[PhilippImhof]

LGTM

[naveen521kk]

LGTM

[behackl]

wow, you two are fast!

[PhilippImhof]

I haven't been contributing for a long time, but was still following the project loosely, so it was a pleasure to get that GitHub message :-) And a pleasure to see that you are still fully engaged

[naveen521kk]

Reviewed on my phone but didn't notice @PhilippImhof also approved it :)

[behackl]

Haha! I've been doing very little over the past 1-2 years I guess, but this summer I have some more time and would like to get some things seriously modernised.

Haven't dared to open a PR yet and still have some things to flesh out for it -- but there is a generous refactor of ManimPango in my pipeline as well. 👀 https://github.com/behackl/ManimPango/tree/rewrite-v2

[naveen521kk]

Let me know once it's ready, I can spend sometime reviewing it. This repo didn't have much changes over the past few years other than KTLO, so it'll be a good refactor.

[behackl]

Will do! (And probably quite soon... :-))