Do not use BigDecimal.new to construct #155

Job	Run time
ruby-versions / Generate Ruby versions	3s
ubuntu-20.04 2.3	46s
ubuntu-20.04 2.4	37s
ubuntu-20.04 2.5	1m 31s
ubuntu-20.04 2.6	1m 18s
ubuntu-20.04 2.7	1m 15s
ubuntu-20.04 3.0	31s
ubuntu-20.04 3.1	39s
ubuntu-20.04 3.2	25s
ubuntu-20.04 head	57s
ubuntu-20.04 jruby	2m 16s
ubuntu-20.04 jruby-head	1m 50s
ubuntu-20.04 truffleruby	54s
ubuntu-20.04 truffleruby-head	1m 29s
ubuntu-22.04 2.3	56s
ubuntu-22.04 2.4	40s
ubuntu-22.04 2.5	1m 16s
ubuntu-22.04 2.6	1m 23s
ubuntu-22.04 2.7	1m 29s
ubuntu-22.04 3.0	25s
ubuntu-22.04 3.1	28s
ubuntu-22.04 3.2	26s
ubuntu-22.04 head	27s
ubuntu-22.04 jruby	1m 39s
ubuntu-22.04 jruby-head	1m 31s
ubuntu-22.04 truffleruby	1m 11s
ubuntu-22.04 truffleruby-head	1m 11s
macos-11 2.3	1m 4s
macos-11 2.4	1m 4s
macos-11 2.5	1m 58s
macos-11 2.6	2m 4s
macos-11 2.7	2m 2s
macos-11 3.0	34s
macos-11 3.1	34s
macos-11 3.2	35s
macos-11 head	39s
macos-11 jruby	1m 26s
macos-11 jruby-head	1m 16s
macos-11 truffleruby	1m 7s
macos-11 truffleruby-head	1m 34s
macos-12 2.3	1m 12s
macos-12 2.4	1m 5s
macos-12 2.5	2m 28s
macos-12 2.6	2m 11s
macos-12 2.7	2m 16s
macos-12 3.0	27s
macos-12 3.1	37s
macos-12 3.2	33s
macos-12 head	50s
macos-12 jruby	1m 36s
macos-12 jruby-head	1m 33s
macos-12 truffleruby	1m 11s
macos-12 truffleruby-head	2m 14s
windows-latest 2.3	2m 19s
windows-latest 2.4	1m 57s
windows-latest 2.5	4m 38s
windows-latest 2.6	5m 38s
windows-latest 2.7	3m 55s
windows-latest 3.0	1m 50s
windows-latest 3.1	2m 18s
windows-latest 3.2	3m 0s
windows-latest head	1m 52s
ubuntu-latest jruby-9.1	1m 56s
ubuntu-latest jruby-9.2	2m 11s
ubuntu-latest jruby-9.3	1m 25s
	1h 34m 42s

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