Doesn't work anymore because of various GA-related deprecations

[jpleboeuf]

Hello,

this theme does not work anymore with recent versions of Hugo because of changes in Hugo's GA internal templates and GA configuration:

• tpl/tplimpl/embedded/templates/google_analytics_async.html has been deprecated since Hugo v0.119.0, and was removed in Hugo v0.125.0, tpl/tplimpl/embedded/templates/google_analytics.html becoming the only GA template.
• site.GoogleAnalytics has been deprecated since Hugo v0.120.0, and its use with the latest Hugo versions currently triggers an error, as per the Hugo deprecation process.

Please see linked PR for a fix.