Introduce pyupgrade

Closes #1742 (closed)

Introducing pyupgrade.

Again, I've made one commit per rule.

ruff.toml

@@ -25,6 +25,8 @@ select = [
     "RET",
     # eradicate
     "ERA",
+    # pyupgrade
+    "UP",
 ]
 ignore = ["E501", "RET502", "RET503"]