patch 8.2.4187: gnuplot file not recognized

Problem:    Gnuplot file not recognized.
Solution:   Recognize ".gnuplot". (closes #9588)
diff --git a/src/version.c b/src/version.c
index 8e659e0..1d5160f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4187,
+/**/
     4186,
 /**/
     4185,