feat!: Update Chef version requirement from 16+ to 18+ (#794)

* Initial plan

* Update Chef version requirement from 16+ to 18+

Co-authored-by: damacus <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: damacus <[email protected]>

Author: Copilot

README.md

@@ -31,7 +31,7 @@ We follow the currently supported versions listed on <https://www.postgresql.org
 
 ### Chef
 
-- Chef 16
+- Chef 18
 
 ### Cookbook Dependencies
 

metadata.rb

@@ -6,7 +6,7 @@
 version           '12.4.0'
 source_url        'https://github.com/sous-chefs/postgresql'
 issues_url        'https://github.com/sous-chefs/postgresql/issues'
-chef_version      '>= 16.0'
+chef_version      '>= 18.0'
 
 depends 'yum', '>= 7.2.0'