Introduce pyupgrade

Closes #1742 (closed)

Introducing pyupgrade.

Again, I've made one commit per rule.

arkindex/documents/management/commands/move_lines_to_parent.py

@@ -6,10 +6,13 @@ from django.core.management.base import BaseCommand, CommandError
 from arkindex.documents.models import ElementType
 from arkindex.project.argparse import CorpusArgument
 
+
 # x and y of top left and bottom right points
-BBox = NamedTuple(
-    "BBox", [("left", int), ("top", int), ("right", int), ("bottom", int)]
-)
+class BBox(NamedTuple):
+    left: int
+    top: int
+    right: int
+    bottom: int
 
 
 def compute_polygon_area(polygon: BBox):