QUIC: Update README and CHANGES for 3.1.7 #1

Job	Run time
run-checker (no-atexit)	4m 37s
run-checker (no-cmp)	1s
run-checker (no-cms)	1s
run-checker (no-ct)	1s
run-checker (no-dtls)	1s
run-checker (no-ec)	3m 36s
run-checker (no-ec2m)	4m 5s
run-checker (no-legacy)	4m 20s
run-checker (no-rfc3779)	4m 29s
run-checker (no-sock)	4m 20s
run-checker (no-srp)	4m 29s
run-checker (no-srtp)	4m 36s
run-checker (enable-ssl-trace)	1s
run-checker (no-tests)	2m 2s
run-checker (no-threads)	4m 37s
run-checker (no-tls)	4m 10s
run-checker (no-tls1_2)	4m 15s
run-checker (no-tls1_3)	4m 14s
run-checker (enable-trace enable-fips)	1s
run-checker (no-ts)	4m 19s
run-checker (no-ui)	4m 19s
	1h 2m 34s

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