patch 9.1.0823: filetype: Zephyr overlay files not recognized

Problem:  filetype: Zephyr overlay files not recognized
Solution: detect '*.overlay' files as dts filetype,
          include syntax tests for DTS files
          (Xudong Zheng)

Reference:
https://docs.zephyrproject.org/latest/build/dts/howtos.html

closes: #15963

Signed-off-by: Xudong Zheng <7pkvm5aw@slicealias.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 74837b3..e670349 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    823,
+/**/
     822,
 /**/
     821,