Remove deprecated method BigDecimal#precs #879

Job	Run time
ruby-versions / Generate Ruby versions	4s
macos-latest 3.1	48s
macos-latest debug	36s
ubuntu-latest 3.3	38s
ubuntu-latest 3.0	36s
ubuntu-latest 2.7	1m 6s
macos-latest 2.7	1m 4s
macos-14 2.7	1m 3s
ubuntu-latest 3.1	40s
ubuntu-latest 3.4	38s
ubuntu-latest 3.2	36s
ubuntu-latest head	35s
macos-latest 3.2	42s
macos-14 head	35s
windows-latest 3.3	2m 51s
macos-14 3.2	26s
macos-14 3.3	31s
ubuntu-latest debug	43s
macos-14 3.0	30s
macos-latest 3.3	32s
macos-14 3.4	29s
macos-latest 3.4	30s
macos-14 3.1	39s
windows-latest head	2m 35s
macos-14 debug	36s
windows-latest 3.4	2m 42s
windows-latest 2.7	4m 52s
macos-latest head	35s
windows-latest mingw	2m 32s
windows-latest mswin	2m 56s
macos-latest 3.0	42s
	34m 22s

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