chore: Add @Suppress {constantProperty} to shaka externs. (#8062) (#8063

)

Add `@suppress {constantProperty}` to shaka externs.

Cherry-picked from v4.13.x, where the original PR was sent by mistake.

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Co-authored-by: Dan Barkhorn <danielbarkhorn@gmail.com>

build/generateExterns.js

@@ -860,9 +860,9 @@ function main(args) {
       '/**\n' +
       ' * @fileoverview Generated externs.  DO NOT EDIT!\n' +
       ' * @externs\n' +
-      ' * @suppress {duplicate} To prevent compiler errors with the\n' +
-      ' *   namespace being declared both here and by goog.provide in the\n' +
-      ' *   library.\n' +
+      ' * @suppress {constantProperty, duplicate} To prevent compiler\n' +
+      ' *   errors with the namespace being declared both here and by\n' +
+      ' *   goog.provide in the library.\n' +
       ' */\n\n' +
       namespaceDeclarations.join('') + '\n' + externs);
 }