deps: react-share 2 -> 5 (drops its defaultProps warnings)

react-share 2.0 shipped function components with defaultProps (CreatedButton,
Icon) -> React-19-blocking warnings on fire-detail pages. v5 is React-18-safe
and drops them. Removed the GooglePlusShareButton/Icon (Google+ is dead;
removed from react-share in v4+); the other 6 buttons (Facebook, Twitter,
Telegram, WhatsApp, Reddit, Email) are API-compatible. Browser-verified 6
buttons render, no defaultProps warnings. REST smoke byte-identical.

package.json

@@ -75,7 +75,7 @@
     "react-resize-detector": "^1.1.0",
     "react-router-bootstrap": "^0.26.3",
     "react-router-dom": "^6.30.4",
-    "react-share": "^2.0.0",
+    "react-share": "^5.3.0",
     "simpl-schema": "^1.5.0",
     "simple-line-icons": "^2.4.1",
     "store": "^2.0.12",