Replace deprecated ArrayBase::uninitialized

[termoshtt]

👎 Deprecated since 0.15.0: This method is hard to use correctly. Use uninit instead.
https://docs.rs/ndarray/0.15.1/ndarray/struct.ArrayBase.html#method.uninit

From #273 and #276

[bluss]

Depends on rust-ndarray/ndarray#1001 in 0.15.2