set .btn-primary:disabled octicon color (#1442)

* set .btn-primary:disabled octicon color

* Create wicked-dolphins-study.md

Co-authored-by: simurai <simulus@gmail.com>

Author: jdanyow

.changeset/wicked-dolphins-study.md

@@ -0,0 +1,5 @@
+---
+"@primer/css": patch
+---
+
+Fix octicon color for disabled .btn-primary

src/buttons/button.scss

@@ -139,6 +139,10 @@
     color: var(--color-btn-primary-disabled-text);
     background-color: var(--color-btn-primary-disabled-bg);
     border-color: var(--color-btn-primary-disabled-border);
+
+    .octicon {
+      color: var(--color-btn-primary-disabled-text);
+    }
   }
 
   &:focus,