author(partial): fix multiple authors in config displayed incorrectly

* is of type `[]interface {}` and not `[]string`

layouts/partials/author.html

@@ -1,7 +1,7 @@
 {{- if or .Params.author .Site.Params.author }}
 {{- $author := (.Params.author | default .Site.Params.author)}}
 {{- $author_type := (printf "%T" $author) }}
-{{- if (eq $author_type "[]string") }}
+{{- if (or (eq $author_type "[]string") (eq $author_type "[]interface {}") ) }}
 {{- (delimit $author ", " ) }}
 {{- else }}
 {{- $author }}