Update gems

Gemfile

@@ -3,6 +3,6 @@ source 'https://rubygems.org'
 ruby '>=2.3'
 
 gem 'scraperwiki', :git => 'https://github.com/openaustralia/scraperwiki-ruby/', :branch => 'morph_defaults'
-gem 'petrify', :git => 'https://github.com/adrianshort/petrify/', :ref => '04aa25b'
+gem 'petrify'
 gem 'rest-client'
 gem 'json'

Gemfile.lock

@@ -1,11 +1,3 @@
-GIT
-  remote: https://github.com/adrianshort/petrify/
-  revision: 04aa25b008188086ed1f4c79ebebfc9f6cbbd75d
-  ref: 04aa25b
-  specs:
-    petrify (0.3.0)
-      haml
-
 GIT
   remote: https://github.com/openaustralia/scraperwiki-ruby/
   revision: fc50176812505e463077d5c673d504a6a234aa78
@@ -31,6 +23,8 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
     netrc (0.11.0)
+    petrify (0.3.1)
+      haml (~> 5.0)
     rest-client (2.0.2)
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
@@ -49,7 +43,7 @@ PLATFORMS
 
 DEPENDENCIES
   json
-  petrify!
+  petrify
   rest-client
   scraperwiki!