Remove dependency on posix-spawn (#18559)

Gemfile

@@ -69,7 +69,6 @@ gem 'nsa'
 gem 'oj', '~> 3.14'
 gem 'ox', '~> 2.14'
 gem 'parslet'
-gem 'posix-spawn'
 gem 'public_suffix', '~> 5.0'
 gem 'pundit', '~> 2.3'
 gem 'premailer-rails'

Gemfile.lock

@@ -509,7 +509,6 @@ GEM
     pg (1.5.6)
     pghero (3.4.1)
       activerecord (>= 6)
-    posix-spawn (0.3.15)
     premailer (1.23.0)
       addressable
       css_parser (>= 1.12.0)
@@ -899,7 +898,6 @@ DEPENDENCIES
   parslet
   pg (~> 1.5)
   pghero
-  posix-spawn
   premailer-rails
   private_address_check (~> 0.5)
   propshaft