Update ndarray-stats requirement from ^0.5 to ^0.6

Updates the requirements on [ndarray-stats](https://github.com/rust-ndarray/ndarray-stats) to permit the latest version.
- [Release notes](https://github.com/rust-ndarray/ndarray-stats/releases)
- [Commits](rust-ndarray/ndarray-stats@0.5.0...0.6.0)

---
updated-dependencies:
- dependency-name: ndarray-stats
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -45,7 +45,7 @@ lazy_static = "^1.4"
 libm = "^0.2"
 macro_const = "^0.1"
 ndarray = "^0.15"
-ndarray-stats = "^0.5"
+ndarray-stats = "^0.6"
 num-complex = "^0.4" # the same version as used by fftw
 num-traits = "^0.2"
 paste = "1"