patch 9.1.1906: filetype: not all Ruby files are recognized

Problem:  filetype: not all Ruby files are recognized
Solution: Detect *.rbi and Brewfile as ruby filetype
          (botantony).

- `rbi` is a file extension used by Sorbet, typechecker for Ruby:
   https://sorbet.org/docs/rbi

- `Brewfile` is a bundler file for Homebrew package manager:
   https://docs.brew.sh/Brew-Bundle-and-Brewfile

closes: #18697

Signed-off-by: botantony <antonsm21@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_filetype.vim

@@ -695,7 +695,9 @@ def s:GetFilenameChecks(): dict<list<string>>
     rrst: ['file.rrst', 'file.srst'],
     rst: ['file.rst'],
     rtf: ['file.rtf'],
-    ruby: ['.irbrc', 'irbrc', '.irb_history', 'irb_history', 'file.rb', 'file.rbw', 'file.gemspec', 'file.ru', 'Gemfile', 'file.builder', 'file.rxml', 'file.rjs', 'file.rant', 'file.rake', 'rakefile', 'Rakefile', 'rantfile', 'Rantfile', 'rakefile-file', 'Rakefile-file', 'Puppetfile', 'Vagrantfile'],
+    ruby: ['.irbrc', 'irbrc', '.irb_history', 'irb_history', 'file.rb', 'file.rbi', 'file.rbw', 'file.gemspec', 'file.ru', 'Gemfile', 'file.builder',
+           'file.rxml', 'file.rjs', 'file.rant', 'file.rake', 'rakefile', 'Rakefile', 'rantfile', 'Rantfile', 'rakefile-file', 'Rakefile-file',
+           'Puppetfile', 'Vagrantfile', 'Brewfile'],
     rust: ['file.rs'],
     sage: ['file.sage'],
     salt: ['file.sls'],

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1906,
 /**/
     1905,
 /**/