Title: GPL Dependencies as Hard Dependencies

[Intron7]

Scirpy currently lists both igraph and python-Levenshtein as hard dependencies. Since these packages are licensed under the GPL, their inclusion could inadvertently impose GPL conditions on Scirpy, which is intended to be BSD licensed.

Potential Impact:

• License Conflict: Incorporating GPL components as mandatory dependencies may force Scirpy to adhere to GPL terms, conflicting with its BSD licensing.
• Distribution Concerns: This could lead to legal and distribution complications, undermining the intended permissive licensing model of Scirpy.

Proposed Solutions:

• Make Dependencies Optional: Consider making igraph and python-Levenshtein optional dependencies to avoid enforcing GPL licensing on the entire package.
• Explore Alternatives: Investigate alternative libraries that provide similar functionality but are licensed under more permissive licenses (e.g., MIT or BSD).

I believe addressing this will help maintain Scirpy's intended BSD license and prevent potential licensing issues. Happy to discuss further or help test any changes proposed.