Log Message:
textproc/ruby-plist: update to 3.6.0

3.6.0 (2020-12-30)

New features and important changes:

* Do not indent multiline string values
  (github.com/patsplat/plist/pull/54)
* Add `Plist::UnimplementedElementError`
  (github.com/patsplat/plist/pull/51)
* Add support for text inside `<![CDATA[ … ]]>`
  (github.com/patsplat/plist/pull/49)

Housekeeping:

* Add Ruby 2.7 and 3.0 to CI (github.com/patsplat/plist/pull/55)
* add docker-compose for development (github.com/patsplat/plist/pull/47)
* Replace `require` with
  `require_relative`(github.com/patsplat/plist/pull/52)