Use shapeless fork in staging

Author: milessabin

.gitmodules

@@ -42,8 +42,8 @@
 	url = https://github.com/dotty-staging/scala-xml
 [submodule "community-build/community-projects/shapeless"]
 	path = community-build/community-projects/shapeless
-	url = https://github.com/milessabin/shapeless
-	branch = shapeless-3
+	url = https://github.com/dotty-staging/shapeless
+	branch = shapeless-3-staging
 [submodule "community-build/community-projects/xml-interpolator"]
 	path = community-build/community-projects/xml-interpolator
 	url = https://github.com/lampepfl/xml-interpolator.git