patch 9.1.0602: filetype: Prolog detection can be improved

Problem:  filetype: Prolog detection can be improved
Solution: update the prolog detection regex
          (igna_martinoli)

related: #10835
related: #15206
closes: #15253

Co-authored-by: clason <c.clason@uni-graz.at>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: igna_martinoli <ignamartinoli@protonmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 5473fe0..5393649 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    602,
+/**/
     601,
 /**/
     600,