Remove version suffix from binstubs

Binstubs are nice but not with openSUSE specific ruby binary names that
break on other environments.

bin/bundle

@@ -1,3 +1,3 @@
-#!/usr/bin/env ruby.ruby2.4
+#!/usr/bin/env ruby
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 load Gem.bin_path('bundler', 'bundle')

bin/rake

@@ -1,4 +1,4 @@
-#!/usr/bin/env ruby.ruby2.4
+#!/usr/bin/env ruby
 require_relative '../config/boot'
 require 'rake'
 Rake.application.run

bin/setup

@@ -1,4 +1,4 @@
-#!/usr/bin/env ruby.ruby2.4
+#!/usr/bin/env ruby
 require 'pathname'
 require 'fileutils'
 include FileUtils

bin/update

@@ -1,4 +1,4 @@
-#!/usr/bin/env ruby.ruby2.4
+#!/usr/bin/env ruby
 require 'pathname'
 require 'fileutils'
 include FileUtils