github actions: update FEDORA_RELEASE to F39, F38 #4304

Job	Run time
checks (make -f Makefile fmt-ci, 1.73.0, rustfmt)	3m 37s
checks (make -f Makefile check-typos, 1.73.0, cargo)	3m 31s
checks_with_tang (TANG_URL=tang RUST_LOG=stratisd=debug make -f Makefile test-clevis-loop, 1.73.0...	14m 56s
python-based-tests	3m 51s
stratis-cli-checks	10m 7s
shell-checks	1m 9s
stratis-min-cli-checks	4m 31s
tests-with-testing-repo (HEAD)	27m 24s
tests-with-testing-repo (v3.6.0)	26m 38s
	1h 35m 44s

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