Update app/src/internal/link.xml

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: AustinBenoit

app/src/internal/link.xml

@@ -3,4 +3,7 @@
     <type fullname="Firebase.Auth.FirebaseAuth" preserve="all"/>
     <type fullname="Firebase.Auth.FirebaseUser" preserve="all"/>
   </assembly>
+  <assembly fullname="Firebase.AppCheck">
+    <type fullname="Firebase.AppCheck.FirebaseAppCheck" preserve="all"/>
+  </assembly>
 </linker>