Rename token fields in DB for User model

[zc-devs]

Clear and concise description of the problem

Token fields was renamed in User model, but not in the database.

Suggested solution

Rename in the database also: access_token, refresh_token.

Alternative

No response

Additional context

#3811

Validations

• Checked that the feature isn't part of the next version already [https://woodpecker-ci.org/faq#which-version-of-woodpecker-should-i-use]
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.