Consider removing FA2 as a dependency as it is not actively maintained and does not pip install from PyPI on Python 3.9+

[dburkhardt]

Describe the bug
To reproduce

1. Have Python 3.9.15
2. Build scenicplus from source
3. Install fails at fa2 dependency due to Problem installing fa2 on Python3.9 bhargavchippada/forceatlas2#34

Workaround:

1. Build fa2 from source
2. Build scenicplus from source

Error output
See bhargavchippada/forceatlas2#34

Additional context

• fa2 doesn't seem to be imported in any module of this package
• Last commit to fa2 is from December 2020
• The lead dev of fa2 acknowledges they are not actively maintaining the package: Status / getting things moving again bhargavchippada/forceatlas2#38

[dburkhardt]

Also, why is scanpy pinned to 1.8.2? It seems like it's only used to log-transform and normalize the data.