(GH-199) Update stack trace tests for Puppet 5.5.18

Previously in commit 074ad0b the stack trace handlers were modified for
Puppet 6.11.0.  That same change is now seen in Puppet 5.5.18.  This commit
modifies the test detection to also detect Puppet 5.5.18+.

Author: glennsarti

spec/debugserver/integration/puppet-debugserver/end_to_end_spec.rb

@@ -33,9 +33,12 @@
   }
 
   def modified_puppet_stack_trace
-    # Due to a modification to the way stack traces are treated in Puppet 6.11.0, the stack size is different
+    # Due to a modification to the way stack traces are treated in Puppet 6.11.0 and 5.5.18, the stack size is different
     # See https://tickets.puppetlabs.com/browse/PUP-10150 for more infomation
-    @modified_puppet_stack_trace ||= Gem::Version.create(Puppet.version) >= Gem::Version.create('6.11.0')
+    pup_ver = Gem::Version.create(Puppet.version)
+    return true if pup_ver >= Gem::Version.create('6.11.0')
+    return true if pup_ver.canonical_segments.first == 5 && pup_ver >= Gem::Version.create('5.5.18')
+    false
   end
 
   context 'Processing an empty manifest with no breakpoints' do