.gitignore fixups

Description

• Remove __pycache__/ from lal*/.gitignore as it's already in the top-level .gitignore
• Add .hypothesis/ to the top-level .gitignore; these directories are created by pytest

API Changes and Justification

Backwards Compatible Changes

• This change does not modify any class/function/struct/type definitions in a public C header file or any Python class/function definitions
• This change adds new classes/functions/structs/types to a public C header file or Python module

Backwards Incompatible Changes

• This change modifies an existing class/function/struct/type definition in a public C header file or Python module
• This change removes an existing class/function/struct/type from a public C header file or Python module

Review Status

cc @adam-mercer