DEV: Fix methods removed in Ruby 3.2 (#15459)

* File.exists? is deprecated and removed in Ruby 3.2 in favor of
File.exist?
* Dir.exists? is deprecated and removed in Ruby 3.2 in favor of
Dir.exist?

lib/stylesheet/manager/builder.rb

@@ -12,7 +12,7 @@ class Stylesheet::Manager::Builder
 
   def compile(opts = {})
     if !opts[:force]
-      if File.exists?(stylesheet_fullpath)
+      if File.exist?(stylesheet_fullpath)
         unless StylesheetCache.where(target: qualified_target, digest: digest).exists?
           begin
             source_map = begin