patch 8.2.3770: new compiler warnings from clang-12 and clang-13

Problem:    New compiler warnings from clang-12 and clang-13.
Solution:   Adjust CI and suppress some warnings. (Ozaki Kiichi, closes #9314)
diff --git a/src/version.c b/src/version.c
index 5aa6ce7..5db7dca 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3770,
+/**/
     3769,
 /**/
     3768,