Fix RuboCop issues (#326)

* Replace `Layout/IndentFirstHashElement` cop with `Layout/FirstHashElementIndentation` cop

The `Layout/IndentFirstHashElement` cop was renamed to `Layout/FirstHashElementIndentation` in RuboCop v0.77.0.

* Remove the unnecessary disabling of Style/IfUnlessModifier.

Author: tatsuyafw

.rubocop.yml

@@ -9,7 +9,7 @@ AllCops:
 Layout/EmptyLinesAroundArguments:
   Enabled: false
 
-Layout/IndentFirstHashElement:
+Layout/FirstHashElementIndentation:
   EnforcedStyle: consistent
 
 Metrics/AbcSize:

lib/grape_entity/entity.rb

@@ -185,7 +185,7 @@ def self.inherited(subclass)
     #   field, typically the value is a hash with two fields, type and desc.
     # @option options :merge This option allows you to merge an exposed field to the root
     #
-    # rubocop:disable Metrics/LineLength, Style/IfUnlessModifier
+    # rubocop:disable Metrics/LineLength
     def self.expose(*args, &block)
       options = merge_options(args.last.is_a?(Hash) ? args.pop : {})
 
@@ -212,7 +212,7 @@ def self.expose(*args, &block)
       @nesting_stack ||= []
       args.each { |attribute| build_exposure_for_attribute(attribute, @nesting_stack, options, block) }
     end
-    # rubocop:enable Metrics/LineLength, Style/IfUnlessModifier
+    # rubocop:enable Metrics/LineLength
 
     def self.build_exposure_for_attribute(attribute, nesting_stack, options, block)
       exposure_list = nesting_stack.empty? ? root_exposures : nesting_stack.last.nested_exposures