Fix regression w/ templates defined in async proc

lib/pure/asyncmacro.nim

@@ -177,7 +177,7 @@ proc processBody(node, retFutureSym: NimNode,
       var newDiscard = node
       result.createVar("futureDiscard_" & $toStrLit(node[0][1]), node[0][1],
                 newDiscard[0], newDiscard, node)
-  of RoutineNodes:
+  of RoutineNodes-{nnkTemplateDef}:
     # skip all the nested procedure definitions
     return
   else: discard

tests/async/ttemplateinasync.nim

@@ -0,0 +1,11 @@
+discard """
+  output: 42
+"""
+
+import asyncdispatch
+
+proc foo(): Future[int] {.async.} =
+  template ret() = return 42
+  ret()
+
+echo (waitFor foo())