Bump requirements for docs building, making dependabot happy

Author: vdboor

Diff for: docs/_ext/djangodummy/requirements.txt

@@ -1,10 +1,10 @@
 # for readthedocs
 # Remaining requirements are picked up from setup.py
-Django==2.2.9
+Django==3.2.3
 django-fluent-utils == 2.0.1
-django-mptt == 0.10.0
-django-parler == 1.9.2
-django-polymorphic == 2.1.1
-django-tag-parser == 3.1
-sphinxcontrib-django == 0.4
-future == 0.17.1
+django-mptt == 0.12.0
+django-parler == 2.2
+django-polymorphic == 3.0.0
+django-tag-parser == 3.2
+sphinxcontrib-django == 0.5.1
+future == 0.18.2