Add ujson to the community build

Author: anatoliykmetyuk

community-build/test/scala/dotty/communitybuild/CommunityBuildTest.scala

@@ -380,7 +380,7 @@ class CommunityBuildTest:
   @Test def utest = projects.utest.run()
   @Test def sourcecode = projects.sourcecode.run()
   @Test def oslib = projects.oslib.run()
-  //@Test def ujson = projects.ujson.run()
+  @Test def ujson = projects.ujson.run()
   // @Test def oslibWatch = projects.oslibWatch.run()
   @Test def stdLib213 = projects.stdLib213.run()
   @Test def shapeless = projects.shapeless.run()