Prefer live timeseries.json

When I was first developing this, and I attempt to access
https://pomber.github.io/covid19/timeseries.json, the browser prevents me from
reading the data because it violates the same origin policy.

I'm learning more about CORS, and I'm going to try consuming this from...
https://wpcarro.dev -> https://pomber.github.io
...instead of...
http://localhost:8000 -> https://pomber.github.io
...because the http -> https protocol violates CORS.

I will not know unless I try, so... bombs away.

covid-uk/src/index.html

@@ -9,7 +9,7 @@
   <script src="./node_modules/chart.js/dist/Chart.bundle.min.js"></script>
   <script>
    var timeseries =
-     fetch('./timeseries.json')
+     fetch('https://pomber.github.io/covid19/timeseries.json')
        .then(res => res.json())
        .then(createChart);