patch 8.2.1906: warning for signed/unsigned

Problem:    Warning for signed/unsigned.
Solution:   Use size_t instead of int. (Mike Williams)
diff --git a/src/version.c b/src/version.c
index 1cde8c7..4acc9c4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1906,
+/**/
     1905,
 /**/
     1904,