Kerberos: support FAST #7422

Job	Run time
CodeQL analysis	2m 18s
Code health check	1m 13s
pyca/cryptography test	23s
Build doc	6m 20s
Type hints check	32s
Check SPDX identifiers	5s
ubuntu-latest 3.8 non_root -K scanner	4m 10s
ubuntu-latest 3.9 non_root -K scanner	4m 34s
ubuntu-latest 3.10 non_root -K scanner	4m 14s
ubuntu-latest 3.11 non_root -K scanner	4m 8s
ubuntu-latest 3.12 non_root -K scanner	4m 28s
ubuntu-22.04 3.7 non_root -K scanner	4m 0s
ubuntu-latest 3.12 root -K scanner	5m 36s
ubuntu-latest pypy3.9 root -K scanner	5m 4s
ubuntu-latest libpcap 3.12 root -K scanner	5m 14s
macos-14 3.12 both -K scanner	6m 9s
ubuntu-latest 3.12 root -k scanner	4m 51s
ubuntu-latest pypy3.9 root -k scanner	4m 29s
macos-14 3.12 both -k scanner	1m 20s
	1h 9m 8s

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