gems ruby 2.4 compatibility

[MontrealSergiy]

Some gems no longer support ruby 2.4.1 recommended in wiki

e.g. sprokets 4 , factory-bot-rails 6

ruby 2.6 is fine.

Alternatively one can set the supported Say gem 'sprockets', '~> 3.7.2'

Update: edited after discussion with Pierre, as it is looks better to use ruby 2.6 as recommended version

[prioux]

We can just change the doc to suggest using Ruby 2.6. I've successfully built CBRAIN with rails 2.6.4; the reason we have 2.4.1 in the doc is that at the time we wanted people note to use a lower version.

[MontrealSergiy]

Then probably better to move to ruby 2.6. I just tried install with 2.6.5 in a vagrant, bundle install runs fine, portal starts well.

Was also able to configure and run local Diagnostics and Bashscriptor tools (with 'Maybe you forgot to add 'touch {cbrain_touch_when_completed}' to your script?' error)

[MontrealSergiy]

btw the vagrant file (fork of Shawn's) is at https://github.com/MontrealSergiy/cbrain-vagrant

It is indeed easier to install than with 2.4 - I vaguely recall some proctable gem irregularities.