feat: ✨ 2.7.0——真值缺省支持 #44

# to view logs

Job	Run time
Julia 1.8 - ubuntu-latest - x64 - push	4m 34s
Julia 1.8 - macOS-latest - x64 - push	6m 10s
Julia 1.8 - windows-latest - x64 - push	5m 16s
Julia 1 - ubuntu-latest - x64 - push	3m 54s
Julia 1 - macOS-latest - x64 - push	12m 42s
Julia 1 - windows-latest - x64 - push	4m 28s
Julia nightly - ubuntu-latest - x64 - push	4m 35s
Julia nightly - macOS-latest - x64 - push	14m 30s
Julia nightly - windows-latest - x64 - push	5m 43s
	1h 1m 52s

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