offlineimap: Strip newlines from offlineimap passwordcommand

[erictapen]

Description

This allows me to use offlineimap with passwordstore. I guess nobody uses a newline in their password?

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all.

Tests seem to be broken atm? attribute 'anything' missing

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

  • Added myself and the module files to .github/CODEOWNERS.

[berbiche]

Thanks for the contribution.

This looks fairly benign.
The Arch wiki has multiple examples with strip() so I assume this is one of those cases.