mill testOnly fail

[pxs7]

gcd.GCDSpec *** ABORTED ***
java.lang.NoClassDefFoundError: chisel3/MultiIOModule
at chiseltest.internal.VerilatorBackendAnnotation$.(Testers2.scala:127)
at chiseltest.internal.VerilatorBackendAnnotation$.(Testers2.scala)
at chiseltest.experimental.ChiselTestCli.$init$(ChiselTestShell.scala:16)
at chiseltest.experimental.ChiselTestShell.(ChiselTestShell.scala:22)
at chiseltest.ChiselScalatestTester$TestBuilder.apply(ChiselScalatestTester.scala:26)
at gcd.GCDSpec.$anonfun$new$1(GCDSpec.scala:24)
at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
...
Cause: java.lang.ClassNotFoundException: chisel3.MultiIOModule
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:445)
at mill.api.ClassLoader$$anon$1.findClass(ClassLoader.scala:47)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at chiseltest.internal.VerilatorBackendAnnotation$.(Testers2.scala:127)
at chiseltest.internal.VerilatorBackendAnnotation$.(Testers2.scala)
at chiseltest.experimental.ChiselTestCli.$init$(ChiselTestShell.scala:16)
at chiseltest.experimental.ChiselTestShell.(ChiselTestShell.scala:22)
at chiseltest.ChiselScalatestTester$TestBuilder.apply(ChiselScalatestTester.scala:26)

[sequencer]

I didn't see any MultiIOModule usage in this repository. IIRC, it has been deprecated in 3.4, and removed in 3.5.