Replace deprecated ".Page.Hugo" usage

The variable ".Hugo" has been deprecated syntax since v0.55. We get a
warning about this each time the site is built:

    Page.Hugo is deprecated and will be removed in a future release. Use the global hugo function.

Tweak the theme to utilise the correct new syntax to remove the errors
making it clearer what is happening when something goes wrong.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

themes/beautifulhugo/i18n/en.yaml

@@ -24,7 +24,7 @@
 
 # Footer
 - id: poweredBy # Accepts HTML
-  translation: '<a href="http://gohugo.io">Hugo v{{ .Hugo.Version }}</a> powered &nbsp;&bull;&nbsp; Theme by <a href="http://deanattali.com/beautiful-jekyll/">Beautiful Jekyll</a> adapted to <a href="https://github.com/halogenica/beautifulhugo">Beautiful Hugo</a>'
+  translation: '<a href="http://gohugo.io">Hugo v{{ .Site.Hugo.Version }}</a> powered &nbsp;&bull;&nbsp; Theme by <a href="http://deanattali.com/beautiful-jekyll/">Beautiful Jekyll</a> adapted to <a href="https://github.com/halogenica/beautifulhugo">Beautiful Hugo</a>'
 
 # Navigation
 - id: toggleNavigation

themes/beautifulhugo/layouts/partials/head.html

@@ -34,7 +34,7 @@
   <meta property="og:type" content="website" />
   <meta property="og:site_name" content="{{ .Site.Title }}" />
 <!-- Hugo Version number -->
-  {{ .Hugo.Generator -}}
+  {{ hugo.Generator -}}
 <!-- Links and stylesheets -->
   <link rel="canonical" href="{{ .URL | absLangURL }}" />
   <link rel="alternate" href="{{ "index.xml" | absLangURL }}" type="application/rss+xml" title="{{ .Site.Title }}">