rename toggle_string_cache to enable_string_cache

[Tian Chu]

Report

when I changed the toggle_string_cache to enable_string_cache in read_gtf.py , another error occurred scan_csv() got an unexpected keyword argument 'sep'

[Gregor Sturm]

This sounds again like an incompatibility of the gtfparse library with polars. See #86

[Tian Chu]

thx, in order not to affect the normal use of other packages, I chose to create a new infercnv-specific environment and specify that the Polars version of 0.15.* is installed and used normally

[Gregor Sturm]

I pinned gtfparse<2 in the latest release which doesn't use polars. This should fix the issue.