vendor_modules: add magic comment

This is a patch to fix an on going issue.  it will be removed the next
time we upgrade augeas_core.  but hopefully an upstream fix[1] is in place
by then

[1]puppetlabs/puppetlabs-augeas_core#60

Bug: T335572
Change-Id: Icba3720beef1a317a9890c17b85106d7f041118e

Author: b4ldr

vendor_modules/augeas_core/lib/puppet/feature/augeas.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'puppet/util/feature'
 
 Puppet.features.add(:augeas, libs: ['augeas'])