Dist::Zilla::Plugin::ContributorCovenant is missing somewhere

While trying to run the tests locally I ran into a problem:

```
$ dzil test
Required plugin Dist::Zilla::Plugin::ContributorCovenant isn't installed.

Run 'dzil authordeps' to see a list of all required plugins.
You can pipe the list to your CPAN client to install or update them:

    dzil authordeps --missing | cpanm
```

but then

```
$  dzil authordeps --missing
```

shows nothing.