Fix migration svg color (#16715)

* Fixed svg color.

* Use --color-text.

Co-authored-by: Lauris BH <lauris@nix.lv>

web_src/less/_repository.less

@@ -3161,6 +3161,7 @@ td.blob-excerpt {
   transition: all .1s ease-in-out;
   box-shadow: none !important;
   border: 1px solid var(--color-secondary);
+  color: var(--color-text);
 }
 
 .repository.migrate .card:hover {