patch 8.2.2053: Vim9: lamba doesn't accept argument types

Problem:    Vim9: lamba doesn't accept argument types.
Solution:   Optionally accept argument types at the script level.
diff --git a/src/eval.c b/src/eval.c
index 6fea436..f23d721 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3266,7 +3266,7 @@
      * Lambda: {arg, arg -> expr}
      * Dictionary: {'key': val, 'key': val}
      */
-    case '{':	ret = get_lambda_tv(arg, rettv, FALSE, evalarg);
+    case '{':	ret = get_lambda_tv(arg, rettv, in_vim9script(), evalarg);
 		if (ret == NOTDONE)
 		    ret = eval_dict(arg, rettv, evalarg, FALSE);
 		break;