Rename buf_api_token to buf_token

[hariso]

... or vice versa.:)

Firstly, thanks for this great product and also for all these GH actions!

I'd like to suggest renaming the configuration parameter buf_api_token to buf_token since that's what most (all?) other Buf actions use (lint, breaking, push).

[emcfarlane]

Hey @hariso , we have recently v1 buf's new GitHub action buf-action. This has the input configuration token. Please take a look!

[hariso]

Whoops, embarrassing :D

Thanks @emcfarlane !