patch 9.1.0187: filetype: no support for Dafny files

Problem:  Dafny files are not recognized.
Solution: Recognize *.dfy files as filetype "dafny" (zeertzjq).

Ref: https://dafny.org/
Ref: https://github.com/mlr-msft/vim-loves-dafny

closes: #14226

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index d090228..ca4ca56 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    187,
+/**/
     186,
 /**/
     185,