[FIX] google_account: accessing the url without any post data

When a user tries to access the URL directly, at that time the value of
dictionary `kw` is not available. The error will be generated.

Error : KeyError: 'state'

This commit will prevent the traceback.

sentry-3947033806

closes odoo/odoo#126640

X-original-commit: 3f651ead
Signed-off-by: Achraf Ben Azzouz (abz) <abz@odoo.com>