This pull request addresses the following warnings enabled since ruby/ruby#4070

* Warnings without this fix 1

```
% ruby -v
ruby 3.1.0dev (2021-02-01T10:54:21Z master 1cdae49d39) [x86_64-darwin20]
% bin/test test/cases/arel/visitors/sqlite_test.rb:36
... snip ...
/Users/yahonda/src/github.com/rails/rails/activerecord/test/cases/arel/support/fake_record.rb:98: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
.

Finished in 0.003538s, 2261.1645 runs/s, 2543.8101 assertions/s.
8 runs, 9 assertions, 0 failures, 0 errors, 0 skips
%
```

* Warnings without this fix 2

```ruby
% ruby -v
ruby 3.1.0dev (2021-02-01T10:54:21Z master 1cdae49d39) [x86_64-darwin20]
% bin/test test/cases/type/adapter_specific_registry_test.rb
Using sqlite3
Run options: --seed 53175

......./Users/yahonda/src/github.com/rails/rails/activerecord/test/cases/type/adapter_specific_registry_test.rb:126: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activemodel/lib/active_model/type/registry.rb:18: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activerecord/test/cases/type/adapter_specific_registry_test.rb:130: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activemodel/lib/active_model/type/registry.rb:18: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
.../Users/yahonda/src/github.com/rails/rails/activerecord/test/cases/type/adapter_specific_registry_test.rb:85: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activemodel/lib/active_model/type/registry.rb:18: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activerecord/test/cases/type/adapter_specific_registry_test.rb:86: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
/Users/yahonda/src/github.com/rails/rails/activemodel/lib/active_model/type/registry.rb:18: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
.

Finished in 0.011424s, 962.8852 runs/s, 2450.9804 assertions/s.
11 runs, 28 assertions, 0 failures, 0 errors, 0 skips
%
```

* Warnings without this fix 3

```ruby
$ cd actionview
$ bin/test test/template/url_helper_test.rb
Run options: --seed 27105

........................../home/yahonda/src/github.com/rails/rails/actionview/test/template/url_helper_test.rb:88: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
.............................../home/yahonda/src/github.com/rails/rails/actionview/test/template/url_helper_test.rb:94: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
..................................................../home/yahonda/src/github.com/rails/rails/actionview/test/template/url_helper_test.rb:71: warning: Passing only keyword arguments to Struct#initialize will behave differently from Ruby 3.2. Please use a Hash literal like .new({k: v}) instead of .new(k: v).
......................

Finished in 0.305066s, 429.4159 runs/s, 580.2032 assertions/s.
131 runs, 177 assertions, 0 failures, 0 errors, 0 skips
$
```

Refer:
ruby/ruby#4070
https://bugs.ruby-lang.org/issues/16806



Co-authored-by: Ryuta Kamizono <kamipo@gmail.com>