add missing @verbose annotations, fix bug#111

[sam-s]

PR Description

Fix https://github.com/mne-tools/mne-connectivity/issues/111

Merge checklist

Maintainer, please confirm the following before merging:

• [ ] All comments resolved
• [ ] This is not your own PR
• [ ] All CIs are happy
• [ ] PR title starts with [MRG]
• [ ] whats_new.rst is updated
• [ ] PR description includes phrase "closes <#issue-number>"

[sam-s]

None of the failures appear to be connected to the PR.