Scale flake8 back to 5.0 #413

Job	Run time
test-postgres (9.5)	3m 25s
test-postgres (9.6)	2m 57s
test-postgres (10)	2m 57s
test-postgres (11)	3m 11s
test-postgres (12)	2m 37s
test-postgres (13)	2m 39s
test-postgres (14)	2m 36s
test-postgres (15)	3m 12s
test-platforms (3.7, ubuntu-latest, asyncio)	2m 18s
test-platforms (3.7, ubuntu-latest, uvloop)	2m 20s
test-platforms (3.7, macos-latest, asyncio)	3m 4s
test-platforms (3.7, macos-latest, uvloop)	3m 14s
test-platforms (3.7, windows-latest, asyncio)	5m 14s
test-platforms (3.8, ubuntu-latest, asyncio)	2m 9s
test-platforms (3.8, ubuntu-latest, uvloop)	2m 10s
test-platforms (3.8, macos-latest, asyncio)	3m 31s
test-platforms (3.8, macos-latest, uvloop)	3m 0s
test-platforms (3.8, windows-latest, asyncio)	5m 49s
test-platforms (3.9, ubuntu-latest, asyncio)	2m 8s
test-platforms (3.9, ubuntu-latest, uvloop)	2m 23s
test-platforms (3.9, macos-latest, asyncio)	2m 58s
test-platforms (3.9, macos-latest, uvloop)	4m 50s
test-platforms (3.9, windows-latest, asyncio)	6m 38s
test-platforms (3.10, ubuntu-latest, asyncio)	2m 8s
test-platforms (3.10, ubuntu-latest, uvloop)	2m 16s
test-platforms (3.10, macos-latest, asyncio)	3m 4s
test-platforms (3.10, macos-latest, uvloop)	2m 49s
test-platforms (3.10, windows-latest, asyncio)	8m 53s
test-platforms (3.11, ubuntu-latest, asyncio)	2m 14s
test-platforms (3.11, ubuntu-latest, uvloop)	2m 10s
test-platforms (3.11, macos-latest, asyncio)	4m 5s
test-platforms (3.11, macos-latest, uvloop)	3m 13s
test-platforms (3.11, windows-latest, asyncio)	4m 53s
Regression Tests	1s
	1h 51m 6s

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