Bump spegel to v0.0.20-k3s1 #7447

Job	Run time
build / Build	9m 35s
Integration Tests (certrotation)	2m 28s
Integration Tests (etcdrestore)	2m 21s
Integration Tests (localstorage)	1m 55s
Integration Tests (startup)	8m 18s
Integration Tests (custometcdargs)	1m 0s
Integration Tests (etcdsnapshot)	8m 40s
Integration Tests (kubeflags)	6m 57s
Integration Tests (longhorn)	3m 32s
Integration Tests (secretsencryption)	3m 44s
Integration Tests (flannelnone)	2m 47s
	51m 17s

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