Pin django-mptt to v0.14.0, for Python 3.8

base_requirements.txt

@@ -23,8 +23,9 @@ django-filter
 django-graphiql-debug-toolbar
 
 # Modified Preorder Tree Traversal (recursive nesting of objects)
+# Pinned to 0.14.0; 0.15.0 requires Python 3.9+
 # https://github.com/django-mptt/django-mptt/blob/main/CHANGELOG.rst
-django-mptt
+django-mptt==0.14.0
 
 # Context managers for PostgreSQL advisory locks
 # https://github.com/Xof/django-pglocks/blob/master/CHANGES.txt

requirements.txt

@@ -4,7 +4,7 @@ django-cors-headers==4.3.0
 django-debug-toolbar==4.2.0
 django-filter==23.3
 django-graphiql-debug-toolbar==0.2.0
-django-mptt==0.15
+django-mptt==0.14.0
 django-pglocks==1.0.4
 django-prometheus==2.3.1
 django-redis==5.4.0