patch 9.1.0995: filetype: shaderslang files are not detected

Problem:  filetype: shaderslang files are not detected
Solution: detect '*.slang' files as shaderslang filetype,
          include a filetype and syntax script (mtvare6)

Reference:
https://shader-slang.com/

closes: #16387

Signed-off-by: mtvare6 <mtvare6@proton.me>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 699ad36..95567b7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    995,
+/**/
     994,
 /**/
     993,