chore: drop Ruby 2.7 support

Ruby 2.7 has been EOL since March 2023, and the CI matrix already only
covers 3.0+. The gemspec was lagging behind reality, claiming 2.7
support while CI never tested it.

- `typesense.gemspec`: bump `required_ruby_version` from `>= 2.7` to
  `>= 3.0`. The `# rubocop:disable Gemspec/RequiredRubyVersion` workaround
  is no longer needed once the floor matches the rubocop target.
- `.rubocop.yml`: bump `TargetRubyVersion` to 3.0.
- `spec/typesense/collections_spec.rb`: rubocop autocorrect from the
  newly-enabled `Style/HashExcept` cop (`Hash#except` was added in 3.0).

Author: erimicel

.rubocop.yml

@@ -2,7 +2,7 @@ plugins: rubocop-rspec
 
 AllCops:
   NewCops: enable
-  TargetRubyVersion: 2.7
+  TargetRubyVersion: 3.0
 
 Style/Documentation:
   Enabled: false

spec/typesense/collections_spec.rb

@@ -36,7 +36,7 @@
   describe '#create' do
     it 'creates a collection and returns it' do
       # since num_documents is a read-only attribute
-      schema_for_creation = company_schema.reject { |key, _| key == 'num_documents' }
+      schema_for_creation = company_schema.except('num_documents')
 
       stub_request(:post, Typesense::ApiCall.new(typesense.configuration).send(:uri_for, '/collections', typesense.configuration.nodes[0]))
         .with(body: schema_for_creation,

typesense.gemspec

@@ -15,9 +15,7 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://typesense.org'
   spec.license       = 'Apache-2.0'
 
-  # rubocop:disable Gemspec/RequiredRubyVersion, Lint/RedundantCopDisableDirective
-  spec.required_ruby_version = '>= 2.7'
-  # rubocop:enable Gemspec/RequiredRubyVersion, Lint/RedundantCopDisableDirective
+  spec.required_ruby_version = '>= 3.0'
 
   spec.files = `git ls-files -z`.split("\x0").reject do |f|
     f.match(%r{^(test|spec|features)/})