patch 9.1.0273: filetype: keymap files are not recognized

Problem:  filetype: keymap files are not recognized
Solution: Detect '*.keymap' files as Device Tree Files
          (0xadk)

closes: #14434

Signed-off-by: 0xadk <0xadk@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/filetype.vim

@@ -663,7 +663,7 @@ au BufNewFile,BufRead *.dsl
 au BufNewFile,BufRead *.dtd			setf dtd
 
 " DTS/DSTI/DTSO (device tree files)
-au BufNewFile,BufRead *.dts,*.dtsi,*.dtso,*.its	setf dts
+au BufNewFile,BufRead *.dts,*.dtsi,*.dtso,*.its,*.keymap	setf dts
 
 " Earthfile
 au BufNewFile,BufRead Earthfile			setf earthfile

src/testdir/test_filetype.vim

@@ -215,7 +215,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     dracula: ['file.drac', 'file.drc', 'filelvs', 'filelpe', 'drac.file', 'lpe', 'lvs', 'some-lpe', 'some-lvs'],
     dtd: ['file.dtd'],
     dtrace: ['/usr/lib/dtrace/io.d'],
-    dts: ['file.dts', 'file.dtsi', 'file.dtso', 'file.its'],
+    dts: ['file.dts', 'file.dtsi', 'file.dtso', 'file.its', 'file.keymap'],
     dune: ['jbuild', 'dune', 'dune-project', 'dune-workspace'],
     dylan: ['file.dylan'],
     dylanintr: ['file.intr'],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    273,
 /**/
     272,
 /**/