patch 8.2.0974: Vim9: memory leak when script var has wrong type

Problem:    Vim9: memory leak when script var has wrong type.
Solution:   Free the variable name.
diff --git a/src/version.c b/src/version.c
index d2f442c..1f91903 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    974,
+/**/
     973,
 /**/
     972,