Update demo.css to fix font links to League Spartan CDN via fontsource - (#1741)

https://cdn.jsdelivr.net/npm/[email protected]/files/

Author: jywarren

examples/demo.css

@@ -1,12 +1,8 @@
 /* https://github.com/theleagueof/league-spartan */
 @font-face {
   font-family: 'League Spartan';
-  src: url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.eot');
-  src: url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.eot?#iefix') format('embedded-opentype'),
-       url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.woff2') format('woff2'),
-       url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.woff') format('woff'),
-       url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.ttf') format('truetype'),
-       url('https://raw.githubusercontent.com/theleagueof/league-spartan/master/_webfonts/leaguespartan-bold.svg#league_spartanbold') format('svg');
+  src: url('https://cdn.jsdelivr.net/npm/fontsource-league-spartan@3/files/league-spartan-latin-600-normal.woff2') format('woff2'),
+       url('https://cdn.jsdelivr.net/npm/fontsource-league-spartan@3/files/league-spartan-latin-600-normal.woff') format('woff');
   font-weight: bold;
   font-style: normal;
 }