patch 9.0.1788: C4090 warnings in strings.c

Problem:  C4090 warnings in strings.c
Solution: Add type casts

closes: #12917

MSVC shows the following warnings:
```
strings.c(2436): warning C4090: 'function': different 'const' qualifiers
strings.c(2774): warning C4090: 'function': different 'const' qualifiers
strings.c(3865): warning C4090: 'function': different 'const' qualifiers
```

So add type casts to suppress them.

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ken .Takata <kentkt@csc.jp>
diff --git a/src/version.c b/src/version.c
index eb65fc1..d6e259c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1788,
+/**/
     1787,
 /**/
     1786,