use SVG for /favicon.ico if browser asks for it

This makes Chromium use the SVG favicon universally including as the
favicon for non-HTML files.

static/build.html

@@ -19,7 +19,7 @@
         <meta property="og:site_name" content="GrapheneOS"/>
         <meta property="og:url" content="https://grapheneos.org/build"/>
         <link rel="canonical" href="https://grapheneos.org/build"/>
-        <link rel="icon" sizes="16x16 24x24 32x32 48x48 64x64" type="image/vnd.microsoft.icon" href="/favicon.ico"/>
+        <link rel="icon" href="/favicon.ico"/>
         <link rel="icon" sizes="any" type="image/svg+xml" href="/favicon.svg"/>
         <link rel="mask-icon" href="/mask-icon.svg" color="#1a1a1a"/>
         <link rel="apple-touch-icon" href="/apple-touch-icon.png"/>