Pass through nil as digest when signing certificates #1078

Job	Run time
openssl-1.0.2u	2m 25s
openssl-1.1.0l	1m 32s
openssl-1.1.1w	1m 49s
openssl-3.0.13	2m 55s
openssl-3.1.5	2m 54s
openssl-3.2.1	3m 26s
openssl-3.3.0	3m 29s
libressl-3.1.5	2m 9s
libressl-3.2.7	2m 15s
libressl-3.3.6	2m 15s
libressl-3.4.3	3m 2s
libressl-3.5.3	2m 21s
libressl-3.6.3	2m 26s
libressl-3.7.3	2m 17s
libressl-3.8.4	2m 11s
libressl-3.9.1	2m 12s
openssl-3.0.13 fips	3m 13s
openssl-3.1.5 fips	2m 51s
openssl-3.2.1 fips	3m 11s
openssl-3.3.0 fips	3m 15s
openssl-head	3m 25s
openssl-head fips	3m 27s
openssl-head no-legacy	3m 33s
ruby-versions / Generate Ruby versions	4s
ubuntu-22.04 2.7	57s
ubuntu-22.04 3.0	1m 11s
ubuntu-22.04 3.1	57s
ubuntu-22.04 3.2	57s
ubuntu-22.04 3.3	1m 22s
ubuntu-22.04 head	1m 35s
ubuntu-22.04 truffleruby	1m 35s
ubuntu-22.04 truffleruby-head	1m 43s
ubuntu-20.04 2.7	1m 21s
ubuntu-20.04 3.0	1m 4s
ubuntu-20.04 3.1	1m 20s
ubuntu-20.04 3.2	1m 17s
ubuntu-20.04 3.3	56s
ubuntu-20.04 head	1m 22s
ubuntu-20.04 truffleruby-head	1m 33s
macos-latest 2.7	1m 14s
macos-latest 3.0	40s
macos-latest 3.1	1m 20s
macos-latest 3.2	48s
macos-latest 3.3	39s
macos-latest head	47s
macos-latest truffleruby-head	1m 5s
windows-latest 2.7	6m 20s
windows-latest 3.0	4m 22s
windows-latest 3.1	4m 51s
windows-latest 3.2	5m 2s
windows-latest 3.3	6m 2s
windows-latest head	4m 7s
windows-latest ucrt	4m 1s
windows-latest mswin	3m 9s
	2h 6m 14s

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