Fixed preconnect template string syntax

[amoshydra]

Summary

Change preconnect string syntax to use template string so that matomoUrl can be correctly injected into the preconnect link element

Related issue

'${matomoUrl}' is not a template string. The plugin will inject a literal "${matomoUrl}" value into the link tag

How is this tested?

Tested locally in a docusaurus project using yarn link with config:

matomo: {
  matomoUrl: 'https://your.matomo.instance/',
  siteId: 'ID',
},

Before fix

After fix

[karser]

Good catch, thank you @amoshydra !