[Scala3] Add BundleSpec and enable Scala3 CI testing (#5050)

Author: adkian-sifive

.github/workflows/test.yml

@@ -89,7 +89,7 @@ jobs:
           $CHISEL_FIRTOOL_PATH/firtool -version >> $GITHUB_STEP_SUMMARY
           echo \`\`\` >> $GITHUB_STEP_SUMMARY
       - name: Test
-        run: ./mill -j0 firrtl.cross[].test -oF + svsim.cross[].test -oF + chisel[].test -oF
+        run: ./mill -j0 firrtl.cross[].test -oF + svsim.cross[].test -oF + chisel[_].test -oF
 
   mima:
     name: binary compatibility checking

src/test/scala-2/chiselTests/BundleSpec.scala renamed to src/test/scala/chiselTests/BundleSpec.scala

@@ -195,8 +195,10 @@ class BundleSpec extends AnyFlatSpec with Matchers with ChiselSim {
     val x = intercept[ChiselException] {
       ChiselStage.emitCHIRRTL(new Example, Array("--throw-on-first-error"))
     }
-    x.getMessage should include(
-      "Called litValue on aggregate MyBundle$1(a=UInt<8>(8), b=Bool(true), c=UInt<4>(DontCare)) contains DontCare"
+    val msg = x.getMessage
+    (msg should include).regex("Called litValue on aggregate MyBundle*")
+    msg should include(
+      "(a=UInt<8>(8), b=Bool(true), c=UInt<4>(DontCare)) contains DontCare"
     )
   }