chore(deps): update Phoenix Pro pin

Advance Phoenix Pro from 5fc672d to 558213d to include the latest attach
menu and Chromium lightbox verification notes. The intervening Pro
changes are documentation only.

Validation: the tracking JSON parses and its commit ID matches Pro HEAD.

Author: abose

tracking-repos.json

@@ -1,5 +1,5 @@
 {
   "phoenixPro": {
-    "commitID": "5fc672d16b2d07c291f6da141e53e41ebfb4bf96"
+    "commitID": "558213deff968d8da653b0fbaa711ef31b464eb9"
   }
 }