[16.0][FIX] auth_saml: update signin method

[vincent-hatakeyama]

Updated the signin method to reflect changes in similar method signin from auth_oauth.

Without the changes, the ORM crashes with psycopg2.errors.InvalidSavepointSpecification when trying to signin.

Fixes #664

[vincent-hatakeyama]

/ocabot rebase patch

[OCA-git-bot]

Hi @vincent-hatakeyama. Your command failed:

Invalid options for command rebase: patch.

Ocabot commands

• ocabot merge major|minor|patch|nobump
• ocabot rebase
• ocabot migration {MODULE_NAME}

More information

• ocabot documentation
• OCA guidelines, specially the "Version Numbers" section.

[vincent-hatakeyama]

/ocabot merge patch

[OCA-git-bot]

What a great day to merge this nice PR. Let's do it! Prepared branch 16.0-ocabot-merge-pr-667-by-vincent-hatakeyama-bump-patch, awaiting test results.

[OCA-git-bot]

Congratulations, your PR was merged at 9039dcb6f28f9a404562290729c22c663659e8ae. Thanks a lot for contributing to OCA. ❤️

[pedrobaeza]

Thanks!