patch 8.2.4601: Vim9: not enough test coverage for executing :def function

Problem:    Vim9: not enough test coverage for executing :def function.
Solution:   Add a few more tests.
diff --git a/src/version.c b/src/version.c
index 0a07093..285b391 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4601,
+/**/
     4600,
 /**/
     4599,