refactor(treewide): formatting and ruff fixes, + manually enabled F401

Signed-off-by: Akhil Narang <me@akhilnarang.dev>

erpnext/accounts/report/payment_ledger/payment_ledger.py

@@ -8,7 +8,7 @@ from frappe import _, qb
 from frappe.query_builder import Criterion
 
 
-class PaymentLedger(object):
+class PaymentLedger:
 	def __init__(self, filters=None):
 		self.filters = filters
 		self.columns, self.data = [], []

erpnext/accounts/report/payment_ledger/test_payment_ledger.py

@@ -1,5 +1,3 @@
-import unittest
-
 import frappe
 from frappe import qb
 from frappe.tests.utils import FrappeTestCase
@@ -57,7 +55,7 @@ class TestPaymentLedger(FrappeTestCase):
 			income_account=self.income_account,
 			warehouse=self.warehouse,
 		)
-		pe = get_payment_entry(sinv.doctype, sinv.name).save().submit()
+		get_payment_entry(sinv.doctype, sinv.name).save().submit()
 
 		filters = frappe._dict({"company": self.company})
 		columns, data = execute(filters=filters)