Move unit test script to plutils project

.github/workflows/ci.yml

@@ -25,7 +25,9 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
+        with:
+          submodules: true
 
       - uses: ruby/setup-ruby@v1
         with:
@@ -54,7 +56,7 @@ jobs:
         run: |
           bundle exec jekyll --version
           bundle exec jekyll build
-          python tests.py
+          python plutils/pltest.py
 
   on_complete:
     name: Notify IRC on Completion

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "plutils"]
+	path = plutils
+	url = https://github.com/allejo/pure-liquid-utils.git

CONTRIBUTING.md

@@ -24,7 +24,7 @@ Got a new feature you'd like to add or a bug fix? Be awesome and submit a PR! A
 
 This project has unit tests to ensure consistent TOC generation and reliability so existing features don't break. This means existing unit tests should **never** be changed in order to make your code pass the tests.
 
-Unit tests are located in the [`_test`](_tests) directory; each file represents a single test. This directory is a Jekyll collection which outputs files, which are run through a Python 2.7 script checking that the actual values are what is expected.
+Unit tests are located in the [`_test`](_tests) directory; each file represents a single test. This directory is a Jekyll collection which outputs files, which are run through a Python 3.8 script checking that the actual values are what is expected.
 
 ### Creating Your Own Test
 
@@ -56,5 +56,5 @@ Build the Jekyll site which processes all of our tests along with our current TO
 
 ```bash
 bundle exec jekyll build
-python tests.py
+python plutils/pltest.py
 ```