github actions: update FEDORA_RELEASE to F39, F38 #4305

Job	Run time
checks_with_tang (TANG_URL=tang RUST_LOG=stratisd=debug make -f Makefile test-clevis-loop, 1.73.0...	14m 33s
checks (make -f Makefile fmt-ci, 1.73.0, rustfmt)	1m 40s
checks (make -f Makefile check-typos, 1.73.0, cargo)	1m 33s
python-based-tests	4m 11s
shell-checks	48s
stratis-cli-checks	9m 39s
stratis-min-cli-checks	3m 32s
tests-with-testing-repo (HEAD)	24m 54s
tests-with-testing-repo (v3.6.0)	24m 44s
	1h 25m 34s

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