gherkin-perl: Update Perl Gherkin implementation

[ehuelsmann]

Summary

Updates the Perl Gherkin implementation

Details

The Perl Gherkin implementation was stale in the following aspects:

1. New test cases had been added which the Perl implementation failed
2. The Rule keyword had been added which the Perl implementation wasn't adapted for yet
3. Gherkin JSON changed (because the project switched to protobuf-serialized-to-JSON)

This PR fixes all three aspects.

How Has This Been Tested?

The PR has been tested using the standard make tests.

Types of changes

• Bug fix (change which un-breaks the implementation).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• The change has been ported to Java.
• The change has been ported to Ruby.
• The change has been ported to JavaScript.
• The change has been ported to Go.
• The change has been ported to .NET.
• I've added tests for my code.
• My change does not require a change to the documentation.
• I have updated the documentation accordingly.
• I have updated the CHANGELOG accordingly.

[ehuelsmann]

With this patch:

$ git diff
diff --git a/gherkin/Makefile b/gherkin/Makefile
index 3942a780..dc5570c9 100644
--- a/gherkin/Makefile
+++ b/gherkin/Makefile
@@ -1,2 +1,2 @@
-LANGUAGES ?= go javascript ruby java elixir
+LANGUAGES ?= perl go javascript ruby java elixir
 include default.mk

This branch builds successfully under make docker-run with the latest docker development image -- including gherkin-perl.