Merge pull request #23 from LunaticMuch/fix/six-module

fix: six module missing
Not sure why this wasn't necessary before, but it definitely needs it now.

requirements.txt

@@ -1,2 +1,3 @@
 pyaml==20.4.0
-docker==4.4.4
+docker==4.4.4
+six==1.16.0

setup.py

@@ -8,7 +8,7 @@ setup(
     license = "GPLv2",
     keywords = "docker yaml container",
     packages = find_packages(),
-    install_requires = ['pyaml>=17.12.1', 'docker>=3.4.1'],
+    install_requires = ['pyaml>=17.12.1', 'docker>=3.4.1','six>=1.16.0'],
     scripts = ['autocompose.py'],
     entry_points={
         'console_scripts': [