Crostini Upgrader Dialog: fix link colors

Fixed: 1119595
Change-Id: Ib977193730a533b29c4dc7f2e73737d56f9eb308
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2366173
Commit-Queue: Nicholas Verne <nverne@chromium.org>
Commit-Queue: Jason Lin <lxj@google.com>
Auto-Submit: Nicholas Verne <nverne@chromium.org>
Reviewed-by: Jason Lin <lxj@google.com>
Cr-Commit-Position: refs/heads/master@{#799980}

chrome/browser/resources/chromeos/crostini_upgrader/app.html

@@ -88,6 +88,11 @@
     justify-content: flex-end;
     margin: 32px 0;
   }
+
+  a[href] {
+    color: var(--cr-link-color);
+    text-decoration: none;
+  }
 </style>
 
 <div id="main">