crypto: always return certificate serial numbers as uppercase #3217

Job	Run time
Build slim tarball	1m 37s
x86_64-darwin: with shared libraries	1h 18m 9s
aarch64-linux: with shared libraries	45m 39s
x86_64-linux: with shared libraries	56m 37s
aarch64-darwin: with shared libraries	1h 8m 29s
	4h 10m 31s

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