patch 8.2.1023: Vim9: redefining a function uses a new index every time

Problem:    Vim9: redefining a function uses a new index every time.
Solution:   When redefining a function clear the contents and re-use the
            index.
diff --git a/src/version.c b/src/version.c
index 870205a..ab618af 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1023,
+/**/
     1022,
 /**/
     1021,