devel/ruby-iruby: update to 0.7.0

0.7.0 (2021-05-28)

Enhancements
* The default backend is changed to IRB (@mrkn)
* Add IRuby::Kernel#switch_backend! method (@mrkn)

Bug Fixes
* Fix the handling of image/svg+xml
  https://github.com/SciRuby/iruby/pull/300,
  https://github.com/SciRuby/iruby/pull/301 (@kojix2)

0.6.1 (2021-05-26)

Bug Fixes
* Follow the messages and hooks orders during execute_request processing
  (@mrkn)

0.6.0 (2021-05-25)

Bug Fixes
* Fix the handling of application/javascript
  https://github.com/SciRuby/iruby/issues/292,
  https://github.com/SciRuby/iruby/pull/294 (@kylekyle, @mrkn)

Enhancements
* Add the initialized event in IRuby::Kernel class
  https://github.com/SciRuby/iruby/pull/168,
  https://github.com/SciRuby/iruby/pull/296 (@Yuki-Inoue, @mrkn)
* Add the following four events https://github.com/SciRuby/iruby/pull/295
  (@mrkn):
  - pre-execute -- occurs before every code execution
  - pre-run-cell -- occurs before every non-silent code execution
  - post-execute -- occurs after every code execution
  - post-run-cell -- occurs after every non-silent code execution
* Replace Bond with IRB in PlainBackend
  https://github.com/SciRuby/iruby/pull/276,
  https://github.com/SciRuby/iruby/pull/297 (@cfis, @mrkn)

(taca)