Pass through nil as digest when signing certificates #1060

Job	Run time
openssl-1.0.2u	6s
openssl-1.1.0l	3s
openssl-1.1.1w	6s
ruby-versions / Generate Ruby versions	4s
openssl-3.0.13	2s
openssl-3.1.5	8s
openssl-3.2.1	5s
openssl-3.3.0	5s
libressl-3.1.5	2m 22s
libressl-3.2.7	2m 12s
libressl-3.3.6	2m 15s
libressl-3.4.3	2m 16s
libressl-3.5.3	2m 16s
libressl-3.6.3	2m 17s
libressl-3.7.3	2m 14s
libressl-3.8.4	2m 10s
libressl-3.9.1	2m 4s
openssl-3.0.13 fips	5s
openssl-3.1.5 fips	5s
openssl-3.2.1 fips	5s
openssl-3.3.0 fips	3s
openssl-head	2m 18s
openssl-head fips	2m 17s
openssl-head no-legacy	2m 19s
ubuntu-22.04 2.7	1m 0s
ubuntu-22.04 3.0	51s
ubuntu-22.04 3.1	1m 1s
ubuntu-22.04 3.2	53s
ubuntu-22.04 3.3	1m 1s
ubuntu-22.04 head	1m 2s
ubuntu-22.04 truffleruby	1m 33s
ubuntu-22.04 truffleruby-head	1m 44s
ubuntu-20.04 2.7	59s
ubuntu-20.04 3.0	57s
ubuntu-20.04 3.1	56s
ubuntu-20.04 3.2	55s
ubuntu-20.04 3.3	49s
ubuntu-20.04 head	1m 1s
ubuntu-20.04 truffleruby-head	1m 36s
macos-latest 2.7	51s
macos-latest 3.0	38s
macos-latest 3.1	40s
macos-latest 3.2	39s
macos-latest 3.3	39s
macos-latest head	41s
macos-latest truffleruby-head	1m 5s
windows-latest 2.7	5m 9s
windows-latest 3.0	3m 59s
windows-latest 3.1	4m 9s
windows-latest 3.2	5m 28s
windows-latest 3.3	5m 49s
windows-latest head	3m 43s
windows-latest ucrt	4m 5s
windows-latest mswin	2m 45s
	1h 24m 35s

Provide feedback