patch 9.1.0926: filetype: Pixi lock files are not recognized

Problem:  filetype: Pixi lock files are not recognized
Solution: detect "pixi.lock" file as yaml filetype
          (Brandon Maier)

Reference:
https://pixi.sh/latest/features/lockfile/

closes: #16212

Signed-off-by: Brandon Maier <brandon.maier@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/filetype.vim

@@ -1873,6 +1873,9 @@ au BufNewFile,BufRead requires/*.txt		setf requirements
 au BufNewFile,BufRead Pipfile			setf toml
 au BufNewFile,BufRead Pipfile.lock		setf json
 
+" Pixi lock
+au BufNewFile,BufRead pixi.lock			setf yaml
+
 " PL/1, PL/I
 au BufNewFile,BufRead *.pli,*.pl1		setf pli
 

src/testdir/test_filetype.vim

@@ -893,7 +893,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     xslt: ['file.xsl', 'file.xslt'],
     yacc: ['file.yy', 'file.yxx', 'file.y++'],
     yaml: ['file.yaml', 'file.yml', 'file.eyaml', 'any/.bundle/config', '.clangd', '.clang-format', '.clang-tidy', 'file.mplstyle', 'matplotlibrc', 'yarn.lock',
-           '/home/user/.kube/config', '.condarc', 'condarc'],
+           '/home/user/.kube/config', '.condarc', 'condarc', 'pixi.lock'],
     yang: ['file.yang'],
     yuck: ['file.yuck'],
     z8a: ['file.z8a'],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    926,
 /**/
     925,
 /**/