Test failure on Julia 1.7 on Windows

[kose-y]

chol_gradient: Test Failed at D:\a\VarianceComponentModels.jl\VarianceComponentModels.jl\test\multivariate_calculus_test.jl:87
  Expression: norm(dL1 - dL2) ≈ 0.0
   Evaluated: 5.551115123125783e-17 ≈ 0.0
Stacktrace:
 [1] macro expansion
   @ C:\hostedtoolcache\windows\julia\1.7.0\x64\share\julia\stdlib\v1.7\Test\src\Test.jl:445 [inlined]
 [2] macro expansion
   @ D:\a\VarianceComponentModels.jl\VarianceComponentModels.jl\test\multivariate_calculus_test.jl:87 [inlined]
 [3] macro expansion
   @ C:\hostedtoolcache\windows\julia\1.7.0\x64\share\julia\stdlib\v1.7\Test\src\Test.jl:1283 [inlined]
 [4] top-level scope
   @ D:\a\VarianceComponentModels.jl\VarianceComponentModels.jl\test\multivariate_calculus_test.jl:79

Looks like we would better change a ≈ b to something like isapprox(a, b; atol=eps()).