wicked_pdf trying to use wrong version of Ruby

I'm getting this error:

Failed to execute: 
["/var/www/apps/menucontrol/shared/bundle/ruby/2.3.0/bin/wkhtmltopdf", "-q", "--margin-top", "3", "--margin-bottom", "29", "--margin-left", "10", "--margin-right", "3", "--footer-html", "file:////tmp/wicked_footer_pdf20181101-1630-5q2bd7.html", "file:////tmp/wicked_pdf20181101-1630-3stg25.html", "/tmp/wicked_pdf_generated_file20181101-1630-c4u87x.pdf"] Error: PDF could not be generated! Command Error: /usr/bin/env: ruby: No such file or directory

configuration:

WickedPdf.config = {
  :exe_path => 'which wkhtmltopdf'.gsub(/\n/, '')
}

I'm using rvm with Ruby 2.5.3 and Rails 4.2.10

Can anyone help me?