patch 8.2.3908: cannot use a script-local function for 'foldtext'

Problem:    Cannot use a script-local function for 'foldtext'.
Solution:   Expand "s:" and "<SID>". (Yegappan Lakshmanan, closes #9411)
diff --git a/src/version.c b/src/version.c
index 7b8b0a6..64086c3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3908,
+/**/
     3907,
 /**/
     3906,