patch 8.2.1808: no test coverage for ":spelldump!"

Problem:    No test coverage for ":spelldump!".
Solution:   Add a test. (Dominique Pellé, closes #7089)
diff --git a/src/version.c b/src/version.c
index daac372..6786727 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1808,
+/**/
     1807,
 /**/
     1806,