upgrade scalacheck to 1.15, test scala.js too

Testing the Scala.js support is a good idea since if we had done it
before we would have caught scala#10177 sooner.

Author: smarter

community-build/community-projects/scalacheck

@@ -172,8 +172,8 @@ object projects:
 
   lazy val scalacheck = SbtCommunityProject(
     project       = "scalacheck",
-    sbtTestCommand   = "jvm/test",
-    sbtPublishCommand = ";set jvm/publishArtifact in (Compile, packageDoc) := false ;jvm/publishLocal"
+    sbtTestCommand   = "test",
+    sbtPublishCommand = "publishLocal"
   )
 
   lazy val scalatest = SbtCommunityProject(
@@ -222,6 +222,7 @@ object projects:
   lazy val minitest = SbtCommunityProject(
     project       = "minitest",
     sbtTestCommand   = "compile",
+    dependencies = List(scalacheck)
   )
 
   lazy val fastparse = SbtCommunityProject(