add scala-collection-compat to community build

Author: SethTisue

.gitmodules

@@ -120,3 +120,6 @@
 [submodule "community-build/community-projects/scala-parallel-collections"]
 	path = community-build/community-projects/scala-parallel-collections
 	url = https://github.com/dotty-staging/scala-parallel-collections.git
+[submodule "community-build/community-projects/scala-collection-compat"]
+	path = community-build/community-projects/scala-collection-compat
+	url = https://github.com/dotty-staging/scala-collection-compat.git

community-build/community-projects/scala-collection-compat

@@ -333,4 +333,9 @@ object projects:
     dependencies     = List(scalacheck)
   )
 
+  lazy val scalaCollectionCompat = SbtCommunityProject(
+    project        = "scala-collection-compat",
+    sbtTestCommand = "compat30/test",
+  )
+
 end projects

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

@@ -114,6 +114,7 @@ class CommunityBuildTestB extends CommunityBuildTest:
   @Test def minitest = projects.minitest.run()
   @Test def munit = projects.munit.run()
   @Test def scalap = projects.scalap.run()
+  @Test def scalaCollectionCompat = projects.scalaCollectionCompat.run()
   @Test def scalaParallelCollections = projects.scalaParallelCollections.run()
   @Test def scalaParserCombinators = projects.scalaParserCombinators.run()
   @Test def ScalaPB = projects.ScalaPB.run()