Fix invalid token error if token has trailing characters
Currently Authenticator would give an "invalid token" error if the token is padded with =
. With this MR a regex rule is applied to the token to filter out =
padding if it's 6, 4, 3 or 1 character long, as those are the only valid paddings that can exist (https://github.com/keepassxreboot/keepassxc/issues/3255).
Fixes #372 (closed)