community build: add scalatestplus-testng

It is a dependency of the ScalaTest test suite since ScalaTest 3.2.4

.gitmodules

@@ -193,3 +193,6 @@
 [submodule "community-build/community-projects/play-json"]
 	path = community-build/community-projects/play-json
 	url = https://github.com/dotty-staging/play-json.git
+[submodule "community-build/community-projects/scalatestplus-testng"]
+	path = community-build/community-projects/scalatestplus-testng
+	url = https://github.com/dotty-staging/scalatestplus-testng.git

community-build/src/scala/dotty/communitybuild/projects.scala

@@ -302,6 +302,13 @@ object projects:
     dependencies      = List(scalatest)
   )
 
+  lazy val scalatestplusTestNG = SbtCommunityProject(
+    project = "scalatestplus-testng",
+    sbtTestCommand = "test",
+    sbtPublishCommand = "publishLocal",
+    dependencies = List(scalatest)
+  )
+
   lazy val scalaXml = SbtCommunityProject(
     project       = "scala-xml",
     sbtTestCommand   = "xml/test",
@@ -739,6 +746,7 @@ def allProjects = List(
   projects.protoquill,
   projects.onnxScala,
   projects.playJson,
+  projects.scalatestplusTestNG,
 )
 
 lazy val projectMap = allProjects.groupBy(_.project)

community-build/test/scala/dotty/communitybuild/CommunityBuildTest.scala

@@ -97,6 +97,7 @@ class CommunityBuildTestA extends CommunityBuildTest:
   @Test def izumiReflect = projects.izumiReflect.run()
   @Test def scalaSTM = projects.scalaSTM.run()
   @Test def scalatest = projects.scalatest.run()
+  @Test def scalatestplusTestNG = projects.scalatestplusTestNG.run()
   // 'Sciss/Lucre' dependencies:
   // @Test def scissEqual      = projects.scissEqual     .run()
   // @Test def scissFingerTree = projects.scissFingerTree.run()