add jdk-21 java version #258

Job	Run time
lint	28s
test (alpine, latest)	3m 2s
test (amazonlinux, latest)	2m 59s
test (enterpriselinux, 8)	2m 56s
test (enterpriselinux, latest)	2m 55s
test (debian, latest)	2m 53s
test (debian, bullseye)	3m 2s
test (fedora, 39)	2m 58s
test (fedora, latest)	2m 57s
test (fedora, rawhide)	3m 6s
test (opensuse, latest)	2m 56s
test (ubuntu, latest)	3m 1s
test (ubuntu, jammy)	3m 0s
test (ubuntu, focal)	3m 8s
	39m 21s

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