Fix test_pkey_rsa.rb in FIPS. #1151

Job	Run time
openssl-1.0.2u	52s
openssl-1.1.0l	54s
openssl-1.1.1w	1m 0s
openssl-3.0.14	58s
openssl-3.1.6	59s
openssl-3.2.2	56s
openssl-3.3.1	55s
openssl-master	3m 37s
libressl-3.1.5	52s
libressl-3.2.7	1m 4s
libressl-3.3.6	1m 2s
libressl-3.4.3	1m 0s
libressl-3.5.3	58s
libressl-3.6.3	59s
libressl-3.7.3	58s
libressl-3.8.4	1m 0s
libressl-3.9.2	59s
openssl-3.0.14 with fips provider	38s
openssl-3.1.6 with fips provider	43s
openssl-3.2.2 with fips provider	37s
openssl-3.3.1 with fips provider	40s
openssl-master with fips provider	3m 17s
openssl-3.3.1 without legacy provider	59s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.7	58s
ubuntu-22.04 3.0	53s
ubuntu-22.04 3.1	1m 3s
ubuntu-22.04 3.2	59s
ubuntu-22.04 3.3	59s
ubuntu-22.04 head	1m 3s
ubuntu-22.04 truffleruby	1m 34s
ubuntu-22.04 truffleruby-head	1m 40s
ubuntu-20.04 2.7	1m 1s
ubuntu-20.04 3.0	57s
ubuntu-20.04 3.1	57s
ubuntu-20.04 3.2	58s
ubuntu-20.04 3.3	56s
ubuntu-20.04 head	58s
ubuntu-20.04 truffleruby	1m 32s
ubuntu-20.04 truffleruby-head	1m 39s
macos-latest 2.7	51s
macos-latest 3.0	39s
macos-latest 3.1	45s
macos-latest 3.2	39s
macos-latest 3.3	41s
macos-latest head	1m 2s
macos-latest truffleruby	1m 1s
macos-latest truffleruby-head	1m 58s
windows-latest 2.7	5m 58s
windows-latest 3.0	3m 41s
windows-latest 3.1	4m 17s
windows-latest 3.2	4m 5s
windows-latest 3.3	4m 14s
windows-latest head	3m 43s
windows-latest ucrt	4m 11s
windows-latest mswin	2m 40s
	1h 24m 32s

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