patch 8.2.3501: tmux filetype dection is incomplete

Problem:    tmux filetype dection is incomplete
Solution:   Also use tmux for files having text after .conf. (Eric Pruitt,
            closes #8971)
diff --git a/src/version.c b/src/version.c
index e09abfa..1f292bb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3501,
+/**/
     3500,
 /**/
     3499,