Fix repo upload fail if no symbolic link to python3

generate_annotation_enums.py was added to repo hook but it specific
pthon instrad of python3, on system without symbolic link to python3 from python, repo upload would failed with a file not found error.

Test: Manual test
Bug: 287123042
Change-Id: I61167c5e97bcabb0b0c1b86971f19ce483ff198f