fix: use the correct copy for a macos host (#24292)

> Related issue: #23621

# Checklist for submitter

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- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/Committing-Changes.md#changes-files)
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- [x] Manual QA for all new/changed functionality

changes/23621-unlock-text

@@ -0,0 +1 @@
+- Fixes an issue with the copy for the activity generated by viewing a locked macOS host's PIN.

frontend/pages/hosts/details/cards/Activity/ActivityItems/UnlockedHostActivityItem/UnlockedHostActivityItem.tsx

@@ -8,9 +8,13 @@ const baseClass = "unlocked-host-activity-item";
 const UnlockedHostActivityItem = ({
   activity,
 }: IHostActivityItemComponentProps) => {
+  let desc = "unlocked this host.";
+  if (activity.details?.host_platform === "darwin") {
+    desc = "viewed the six-digit unlock PIN for this host.";
+  }
   return (
     <HostActivityItem className={baseClass} activity={activity}>
-      <b>{activity.actor_full_name}</b> unlocked this host.
+      <b>{activity.actor_full_name} </b> {desc}
     </HostActivityItem>
   );
 };