Fix apply auto insertion warnings

[xuwei-k]

[warn] -- Warning: /home/runner/work/sbinary/sbinary/core/src/test/scala/binaryTests.scala:190:50 
[warn] 190 |  implicit val BazFormat: Format[Baz] = viaString(Baz)
[warn]     |                                                  ^^^
[warn]     |The method `apply` is inserted. The auto insertion will be deprecated, please write `sbinary.FormatTests.Baz.apply` explicitly.
[warn] -- Warning: /home/runner/work/sbinary/sbinary/core/src/test/scala/binaryTests.scala:191:51 
[warn] 191 |  implicit val BifFormat: Format[Bif] = asProduct2(Bif)(x => (x.i, x.j))
[warn]     |                                                   ^^^
[warn]     |The method `apply` is inserted. The auto insertion will be deprecated, please write `sbinary.FormatTests.Bif.apply` explicitly.

[eed3si9n]

Thanks!