[weblate] Declare constraint for Python six

For some reason, our script is not detecting some dependency constraints
correctly, so i'm pinning this one manually.

From: https://github.com/django-compressor/django-compressor/blob/2.4/setup.py#L148

manifests/weblate/debian_packages.pp

@@ -26,7 +26,6 @@ class tails::weblate::debian_packages () {
     'python3-requests',
     'python3-requests-oauthlib',
     'python3-ruamel.yaml',
-    'python3-six',
     'python3-sqlparse',
     'python3-tz',
     'python3-whoosh',

manifests/weblate/python_modules.pp

@@ -60,7 +60,7 @@ class tails::weblate::python_modules () {
   tails::pip_package_from_repo { 'django-compressor':
     version => '2.4',  # >=2.1.1
     url     => 'https://github.com/django-compressor/django-compressor',
-    require => [Exec['pip_install_django-appconf'], Exec['pip_install_rjsmin']],
+    require => [Exec['pip_install_django-appconf'], Exec['pip_install_rjsmin'], Exec['pip_install_six']],
   }
 
   tails::pip_package_from_repo { 'django-crispy-forms':
@@ -139,16 +139,21 @@ class tails::weblate::python_modules () {
     url     => 'https://github.com/WeblateOrg/siphashc',
   }
 
+  tails::pip_package_from_repo { 'six':
+    version => '1.15.0',  # >=1.11.0,>=1.7.0
+    url     => 'https://github.com/benjaminp/six',
+  }
+
   tails::pip_package_from_repo { 'social-auth-app-django':
     version => '3.4.0',  # >=3.1.0
     url     => 'https://github.com/python-social-auth/social-app-django',
-    require => [Exec['pip_install_social-auth-core']],
+    require => [Exec['pip_install_six'], Exec['pip_install_social-auth-core']],
   }
 
   tails::pip_package_from_repo { 'social-auth-core':
     version => '3.3.3',  # >=3.1.0
     url     => 'https://github.com/python-social-auth/social-core',
-    require => [Exec['pip_install_oauthlib'], Exec['pip_install_python3-openid']],
+    require => [Exec['pip_install_oauthlib'], Exec['pip_install_six'], Exec['pip_install_python3-openid']],
   }
 
   tails::pip_package_from_repo { 'translate-toolkit':

scripts/weblate/override.yaml

@@ -48,6 +48,8 @@ pip:
       - <3.0  # Bigger versions require Python >=3.6
   rjsmin:
     url: https://github.com/ndparker/rjsmin
+  six:
+    additional_condition: [ '>=1.12.0' ]  # for django-compressor
   translate-toolkit:
     url: https://github.com/translate/translate
   translation-finder: