[test] Mark freetype test as crossplaform. NFC

See emscripten-core#22585 (comment)

Author: sbc100

test/test_other.py

@@ -2484,6 +2484,7 @@ def test_bzip2(self):
 
   @with_all_sjlj
   @requires_network
+  @crossplatform
   def test_freetype(self):
     # copy the Liberation Sans Bold truetype file located in the
     # <emscripten_root>/test/freetype to the compilation folder