layouts: Remove a few more references to GooglePlus

The sharing icons were removed in 2019, but these remained.

layouts/_default/list.html

@@ -14,9 +14,6 @@
   {{- if not .Date.IsZero }}
   "dateModified": {{ .Date.Format $ISO8601 }},
   {{- end }}
-  {{- with .Site.Social.GooglePlus }}
-  "publisher": "{{ printf "%s" . }}",
-  {{- end }}
   {{- /* all of the site's categories/tags, from Hugo's tpl/template_embedded.go */}}
   "keywords": "{{ range $plural, $terms := .Site.Taxonomies }}{{ range $term, $val := $terms }}{{ printf "%s," $term }}{{ end }}{{ end }}"
   {{- with .Site.Params.description -}}

layouts/_default/single.html

@@ -32,9 +32,6 @@
   {{- if not .Lastmod.IsZero }}
   "dateModified": {{ .Lastmod.Format $ISO8601 }},
   {{- end }}
-  {{- with .Site.Social.GooglePlus }}
-  "publisher": "{{ printf "%s" . }}",
-  {{- end }}
   "author": {
     "@type": "Person",
     "name": "{{ .Params.author | default .Site.Params.author }}"