Dockerfile.ci: rubygems-update fix to 2.7.8

[eguzki]

Fix rubygems-update to 2.7.8

rubygems-update ~> 3.0 requires ruby >= 2.3. Breaks our tests for ruby 2.2

Step 53/63 : RUN sudo chown -R "${USER_NAME}": /tmp/apisonator     && cd /tmp/apisonator     && rbenv_update_env

 ---> Running in 8586b5cf70e6


Downloading ruby-2.2.4.tar.bz2...

-> https://cache.ruby-lang.org/pub/ruby/2.2/ruby-2.2.4.tar.bz2

Installing ruby-2.2.4...


WARNING: ruby-2.2.4 is nearing its end of life.

It only receives critical security updates, no bug fixes.

Installed ruby-2.2.4 to /home/ruby/.rbenv/versions/2.2.4


ERROR:  Error installing rubygems-update:

    rubygems-update requires Ruby version >= 2.3.0.

ERROR:  While executing gem ... (NoMethodError)

    undefined method `version' for nil:NilClass

Updating rubygems-update

The command '/bin/sh -c sudo chown -R "${USER_NAME}": /tmp/apisonator     && cd /tmp/apisonator     && rbenv_update_env' returned a non-zero code: 1

[eguzki]

credits to @davidor 🎖️

[unleashed]

you can still do < 3.0.0?

[davidor]

Looks like it's not possible to specify the version like that.

[unleashed]

Ok, just make sure you remove this when upgrading Ruby to 2.3+.

[eguzki]

ups, forgot about our bors friend :'(