Allow SP certificates to be OpenSSL::X509::Certificate #389

Job	Run time
Unit test (ubuntu-20.04, 2.1)	57s
Unit test (ubuntu-20.04, 2.2)	1m 4s
Unit test (ubuntu-20.04, 2.3)	1m 4s
Unit test (ubuntu-20.04, 2.4)	58s
Unit test (ubuntu-20.04, 2.5)	28s
Unit test (ubuntu-20.04, 2.6)	30s
Unit test (ubuntu-20.04, 2.7)	28s
Unit test (ubuntu-20.04, 3)	15s
Unit test (ubuntu-20.04, 3.1)	17s
Unit test (ubuntu-20.04, 3.2)	16s
Unit test (ubuntu-20.04, 3.3)	16s
Unit test (ubuntu-20.04, jruby-9.1)	54s
Unit test (ubuntu-20.04, jruby-9.2)	1m 2s
Unit test (ubuntu-20.04, jruby-9.3)	53s
Unit test (ubuntu-20.04, jruby-9.4)	54s
Unit test (ubuntu-20.04, truffleruby)	1m 47s
Unit test (macos-latest, 2.6)	37s
Unit test (macos-latest, 2.7)	43s
Unit test (macos-latest, 3)	19s
Unit test (macos-latest, 3.1)	20s
Unit test (macos-latest, 3.2)	19s
Unit test (macos-latest, 3.3)	21s
Unit test (macos-latest, jruby-9.3)	34s
Unit test (macos-latest, jruby-9.4)	40s
Unit test (macos-latest, truffleruby)	1m 32s
Unit test (windows-latest, 2.2)	1m 51s
Unit test (windows-latest, 2.3)	1m 21s
Unit test (windows-latest, 2.4)	1m 20s
Unit test (windows-latest, 2.5)	2m 35s
Unit test (windows-latest, 2.6)	2m 18s
Unit test (windows-latest, 2.7)	3m 11s
Unit test (windows-latest, 3)	1m 35s
Unit test (windows-latest, 3.1)	59s
Unit test (windows-latest, 3.2)	1m 16s
Unit test (windows-latest, 3.3)	2m 24s
finish	0s
	36m 18s

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