fix: loading the correct internal Google Analytics template for v4 token

Added if-clause to check prefix of googleAnalytics variable for v4 format ("G-"). Loading according internal template as specified in hugo docs.

Reviewed-by: Vladimir Doroch
Refs: #339

layouts/partials/footer.html

@@ -32,7 +32,11 @@
 </footer>
 {{- partial "medium-zoom.html" .context -}}
 {{- partial "math.html" .context -}}
-{{- template "_internal/google_analytics_async.html" .context -}}
+{{- if (hasPrefix .context.Site.GoogleAnalytics "G-") -}}
+  {{- template "_internal/google_analytics.html" .context -}}
+{{- else -}}
+  {{- template "_internal/google_analytics_async.html" .context -}}
+{{- end -}}
 {{- if and (hugo.IsProduction) (.context.Site.Params.gtagId) -}}
   {{ partial "google-analytics-gtag-async.html" .context }}