Update pgproto and add tests for client_encoding #448

Job	Run time
test-postgres (9.5)	21s
test-postgres (9.6)	24s
test-postgres (10)	2m 25s
test-postgres (11)	2m 38s
test-postgres (12)	2m 29s
test-postgres (13)	28s
test-postgres (14)	30s
test-postgres (15)	23s
test-platforms (3.8, ubuntu-latest, asyncio)	2m 11s
test-platforms (3.8, ubuntu-latest, uvloop)	2m 10s
test-platforms (3.8, macos-latest, asyncio)	2m 16s
test-platforms (3.8, macos-latest, uvloop)	1s
test-platforms (3.8, windows-latest, asyncio)	2m 11s
test-platforms (3.9, ubuntu-latest, asyncio)	2m 18s
test-platforms (3.9, ubuntu-latest, uvloop)	2m 13s
test-platforms (3.9, macos-latest, asyncio)	1s
test-platforms (3.9, macos-latest, uvloop)	1s
test-platforms (3.9, windows-latest, asyncio)	2m 11s
test-platforms (3.10, ubuntu-latest, asyncio)	2m 22s
test-platforms (3.10, ubuntu-latest, uvloop)	2m 18s
test-platforms (3.10, macos-latest, asyncio)	2m 15s
test-platforms (3.10, macos-latest, uvloop)	1m 20s
test-platforms (3.10, windows-latest, asyncio)	2m 14s
test-platforms (3.11, ubuntu-latest, asyncio)	2m 4s
test-platforms (3.11, ubuntu-latest, uvloop)	2m 10s
test-platforms (3.11, macos-latest, asyncio)	2m 15s
test-platforms (3.11, macos-latest, uvloop)	2m 15s
test-platforms (3.11, windows-latest, asyncio)	2m 10s
Regression Tests	0s
	46m 34s

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