remove `final` modifier from `object`

[xuwei-k]

prepare Scala 3, sbt 2.x build.

Welcome to Scala 3.3.4 (21.0.4, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
                                                                                                                                             
scala> final object A
1 warning found
-- [E147] Syntax Warning: ------------------------------------------------------
1 |final object A
  |^^^^^
  |Modifier final is redundant for this definition