patch 8.2.0570: Vim9: no error when omitting type from argument

Problem:    Vim9: no error when omitting type from argument.
Solution:   Enforce specifying argument types.
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 062502f..dad4dee 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -859,11 +859,11 @@
   assert_equal(88, --nr)
 enddef
 
-def Echo(arg): string
+def Echo(arg: any): string
   return arg
 enddef
 
-def s:EchoArg(arg): string
+def s:EchoArg(arg: any): string
   return arg
 enddef
 
@@ -991,6 +991,7 @@
   assert_equal(123, d.key)
 enddef
 
+
 func Test_expr7_trailing_fails()
   call CheckDefFailureList(['let l = [2]', 'l->{l -> add(l, 8)}'], 'E107')
   call CheckDefFailureList(['let l = [2]', 'l->{l -> add(l, 8)} ()'], 'E274')