patch 9.1.0536: filetype: zone files are not recognized

Problem:  filetype: zone files are not recognized
          (rpdprd)
Solution: Detect '*.zone' files as bindzone filetype

fixes: #14222

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_filetype.vim

@@ -121,7 +121,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     beancount: ['file.beancount'],
     bib: ['file.bib'],
     bicep: ['file.bicep', 'file.bicepparam'],
-    bindzone: ['named.root', '/bind/db.file', '/named/db.file', 'any/bind/db.file', 'any/named/db.file'],
+    bindzone: ['named.root', '/bind/db.file', '/named/db.file', 'any/bind/db.file', 'any/named/db.file', 'foobar.zone'],
     bitbake: ['file.bb', 'file.bbappend', 'file.bbclass', 'build/conf/local.conf', 'meta/conf/layer.conf', 'build/conf/bbappend.conf', 'meta-layer/conf/distro/foo.conf'],
     blade: ['file.blade.php'],
     blank: ['file.bl'],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    536,
 /**/
     535,
 /**/