Fix missing `args` input in `action.yml`

[MarcMogdanz]

I've seen you've added the option to add custom args in 1.5.0 (e3c7eb42d842357ee55e9148a9861386489661c5) but you forgot to add the new option to the action.yml and therefor it throws an error when using it:

##[warning]Unexpected input 'args', valid inputs are ['github_token', 'mac_certs', 'mac_certs_password', 'release', 'windows_certs', 'windows_certs_password', 'package_root', 'build_script_name', 'skip_build', 'use_vue_cli', 'app_root']
Run samuelmeuli/action-electron-builder@v1

Will run NPM commands in directory "."

As you can see in this pipeline run here.

I've just added the option and already ran it and it worked but feel free to test it yourself before merging! Thanks for your action!

[samuelmeuli]

Thank you!