vim-patch:9.1.0735: filetype: salt files are not recognized

Problem:  filetype: salt files are not recognized
Solution: Detect '*.sls' files as filetype salt,
          include a syntax script (Gregory Anders)

closes: vim/vim#15689

89b9bb4ac8

Co-authored-by: Gregory Anders <greg@gpanders.com>

runtime/lua/vim/filetype.lua

@@ -1024,6 +1024,7 @@ local extension = {
   rake = 'ruby',
   rs = 'rust',
   sage = 'sage',
+  sls = 'salt',
   sas = 'sas',
   sass = 'sass',
   sa = 'sather',