Wrong default value for `cname` in `schema.json`

[JohannesHoppe]

Error: Property 'cname' does not match the schema. 'false' should be a 'string'.

Solved it by adding cname flag manually as github.com along with base-href.

Originally posted by @batbrain9392 in https://github.com/angular-schule/angular-cli-ghpages/issues/145#issuecomment-1050404723

see https://github.com/angular-schule/angular-cli-ghpages/blob/76753b0dcd66e4b09007c6dd4bf0615ebc8a488f/src/deploy/schema.json#L51-L55

[JohannesHoppe]

The typings here are indeed wrong, an empty string should do the trick.