[FIX] mail_environment: default computation

[gurneyalex]

fix the implementation of _compute_default_authentication to match what is expected by the mixin

[gurneyalex]

/ocabot merge patch

[OCA-git-bot]

This PR looks fantastic, let's merge it!
Prepared branch 15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch, awaiting test results.

[OCA-git-bot]

@gurneyalex The merge process could not start, because command git push origin :15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch failed with output:

To https://github.com/OCA/server-env
 ! [remote rejected] 15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch (cannot lock ref 'refs/heads/15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch': unable to resolve reference 'refs/heads/15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch')
error: failed to push some refs to 'https://***@github.com/OCA/server-env'

[OCA-git-bot]

@gurneyalex The merge process could not be finalized, because command git push origin :15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch failed with output:

To https://github.com/OCA/server-env
 ! [remote rejected] 15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch (cannot lock ref 'refs/heads/15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch': unable to resolve reference 'refs/heads/15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch')
error: failed to push some refs to 'https://***@github.com/OCA/server-env'

[OCA-git-bot]

It looks like something changed on 15.0 in the meantime.
Let me try again (no action is required from you).
Prepared branch 15.0-ocabot-merge-pr-194-by-gurneyalex-bump-patch, awaiting test results.

[OCA-git-bot]

Congratulations, your PR was merged at b6963c5. Thanks a lot for contributing to OCA. ❤️