[MRG] Add return type to TableList __getitem__ method

[16dprice]

This PR simply adds a return type to the TableList __getitem__ method so that when you write code like:

tables = camelot.read_pdf(file_path, pages=pages)
table1 = tables[0]

you get automatic type inference on the table1 variable.

[MartinThoma]

Hey!

As camelot is dead, we try to build a maintained fork at pypdf_table_extraction.

Do you want to open the PR against that branch so that we can merge your improvement?