Fix the issue that excluded files in rspec-rails did not work

`bin/*` and `db/schema.rb` were not excluded.
Exclude files should be absolute paths internally, so it fixes to call the `make_excludes_absolute` method.

Ref: rubocop/rubocop@cb63798

lib/rubocop/rails/inject.rb

@@ -8,7 +8,7 @@ module Inject
       def self.defaults!
         path = CONFIG_DEFAULT.to_s
         hash = ConfigLoader.send(:load_yaml_configuration, path)
-        config = Config.new(hash, path)
+        config = Config.new(hash, path).tap(&:make_excludes_absolute)
         puts "configuration from #{path}" if ConfigLoader.debug?
         config = ConfigLoader.merge_with_default(config, path, unset_nil: false)
         ConfigLoader.instance_variable_set(:@default_configuration, config)

spec/rubocop/rails/inject_spec.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Rails::Inject do
+  describe '#defaults!' do
+    before { allow(Dir).to receive(:pwd).and_return('/home/foo/project') }
+
+    it 'makes excludes absolute' do
+      configuration = described_class.defaults!
+      expect(configuration['AllCops']['Exclude'])
+        .to eq [
+          '/home/foo/project/bin/*',
+          '/home/foo/project/db/schema.rb'
+        ]
+    end
+  end
+end