Log Message:
devel/ruby-backports: update to 3.20.1

## [3.20.1](https://github.com/marcandre/backports/compare/v3.20.0...v3.20.1) - \ 
2021-01-03

### Fixed

* Added `Ractor.[]` and `[]=` [#161]
* `Ractor.current` fixed from threads [#161]

## [3.20.0](https://github.com/marcandre/backports/compare/v3.19.0...v3.20.0) - \ 
2020-12-30

### Added

Ractor backport (all methods)

## [3.19.0](https://github.com/marcandre/backports/compare/v3.19.0...v3.18.2) - \ 
2020-12-28

### Added

* Ruby 3.0 backports

  * Env
    * `except`

  * Hash
    * `except`
    * `transform_keys`, `transform_keys!` (with hash argument)

  * Symbol
    * `name`

* Ruby 2.3 backports

  * Queue
    * `close`, `closed?` (affects `push`, `pop` and aliases)