patch 8.2.1387: Vim9: cannot assign to single letter variable with type

Problem:    Vim9: cannot assign to single letter variable with type.
Solution:   Exclude the colon from the variable name. (closes #6647)
diff --git a/src/version.c b/src/version.c
index e251ba8..11b6862 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1387,
+/**/
     1386,
 /**/
     1385,