Allow for `fixup! {conventional}`

[JP-Ellis]

It would appear to me that the following combination of configuration options

style = "conventional"
no_fixup = false

Should allow for fixup to conventional commits. Unfortunately, this is not what is observed:

❯ echo 'fixup! chore: testing' | committed   
-: error Commit is not in Conventional format: Missing type in the commit summary, expected `type: description`

My expectation is that a fixup to a conventional commit should be allowed, and that committed should verify the message to be of the form fixup! type: description.