Add __pycache__ to the gitignore (#56134)

Summary:
Pull Request resolved: #56134

The `__pycache__` is generated when I run the script locally. This should be added to `.gitignore`.

Changelog:
[Internal]

Reviewed By: huntie

Differential Revision: D97119516

fbshipit-source-id: f52160c43d537543ad1459ca7a07996de8ab5e7f

Author: coado

.gitignore

@@ -177,6 +177,9 @@ fix_*.patch
 # [Experimental] Generated TS type definitions
 /packages/**/types_generated/
 
+# Python
+__pycache__/
+
 # Doxygen XML output used for C++ API tracking
 /packages/react-native/**/api/xml
 /packages/react-native/**/api/codegen