Fix testing by requiring recent tox version

.gitlab-ci.yml

@@ -3,6 +3,7 @@ default:
   # Make sure each step is executed in a virtual environment with some basic dependencies present
   before_script:
     - python --version # For debugging
+    - tox --version
   cache:
     paths:
       - .cache/pip

README.md

@@ -43,4 +43,5 @@ This project is licensed under the Apache License Version 2.0
 
 ## Releases
 
+- 0.2 - Ensure requirements.txt dependencies are installed
 - 0.1 - Initial release from separating into own repository

tox.ini

 [tox]
 # Generative environment list to test all supported Python versions
 envlist = py3{7,8,9,10,11},black,pep8,pylint
-minversion = 3.28.0
+minversion = 4.3.3
 
 [testenv]
 usedevelop = True