Python 3.11 in Dockerfile plus fixes and lib updates

[1.3]

Fixed

• Typo in instructions to download genes in README document

Changed

• Code formatted with black and black check GitHub action
• Renamed schug.load.ensembl.fetch_ensembl_exon_lines function to schug.load.ensembl.fetch_ensembl_exons
• Upgraded Python version from 3.8 to 3.11 in Dockerfile
• Updated several python libraries in poetry.lock