Improve .haml-lint.yml, simplify the haml_lint task and remove CHANGELOG entry

.haml-lint.yml

-# Default application configuration that all configurations inherit from.
-#
-# This is an opinionated list of which hooks are valuable to run and what their
-# out of the box settings should be.
-
 # Whether to ignore frontmatter at the beginning of HAML documents for
 # frameworks such as Jekyll/Middleman
 skip_frontmatter: false
 exclude:
   - 'vendor/**/*'
+  - 'spec/**/*'
 
 linters:
   AltText:

CHANGELOG

@@ -20,7 +20,6 @@ v 8.12.0 (unreleased)
   - Fix pagination on user snippets page
   - Fix sorting of issues in API
   - Ensure specs on sorting of issues in API are deterministic on MySQL
-  - Use haml_lint for views linting
   - Escape search term before passing it to Regexp.new !6241 (winniehell)
   - Fix pinned sidebar behavior in smaller viewports !6169
   - Fix file permissions change when updating a file on the Gitlab UI !5979

lib/tasks/haml-lint.rake

 unless Rails.env.production?
   require 'haml_lint/rake_task'
 
-  HamlLint::RakeTask.new do |t|
-    t.config = '.haml-lint.yml'
-    t.files = ['app/views']
-  end
+  HamlLint::RakeTask.new
 end