style(theme): restore the external link icon color from previous version (#2571)

src/client/theme-default/components/VPDoc.vue

@@ -205,5 +205,6 @@ const pageName = computed(() =>
 
 .external-link-icon-enabled :is(.vp-doc a[href*='://'], .vp-doc a[target='_blank'])::after {
   content: '';
+  color: currentColor;
 }
 </style>

src/client/theme-default/styles/components/vp-doc.css

@@ -546,6 +546,7 @@
   width: 11px;
   height: 11px;
   background: currentColor;
+  color: var(--vp-c-text-3);
   flex-shrink: 0;
   --icon: url("data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' %3E%3Cpath d='M0 0h24v24H0V0z' fill='none' /%3E%3Cpath d='M9 5v2h6.59L4 18.59 5.41 20 17 8.41V15h2V5H9z' /%3E%3C/svg%3E");
   -webkit-mask-image: var(--icon);