Bug: mean over dimension does not remove dimension

[briochemc]

Contrary to what the docs say here: https://juliadatacubes.github.io/YAXArrays.jl/stable/UserGuide/compute.html#mapslices

That is, copying the docs:

mapslices(mean, a, dims="time")

retains the dimension attribute (the time dimension does not match the array size anymore):

┌ 1×10×15 YAXArray{Float64, 3} ┐
├──────────────────────────────┴───────────────────────────────────────── dims ┐
  ↓ time Sampled{IntervalSets.ClosedInterval{Date}} [2022-01-01 .. 2022-01-30] ForwardOrdered Irregular Intervals{Start},
  → lon Sampled{Float64} 1.0:1.0:10.0 ForwardOrdered Regular Points,
  ↗ lat Sampled{Float64} 1.0:0.2857142857142857:5.0 ForwardOrdered Regular Points
├─────────────────────────────────────────────────────────────── loaded lazily ┤
  data size: 1.17 KB
└──────────────────────────────────────────────────────────────────────────────┘

That's a bug right?

[briochemc]

As noted in #546 and #544, this used to work in v0.6.1:

julia> using YAXArrays, Statistics

julia> a = YAXArray(rand(10, 20, 5))
┌ 10×20×5 YAXArray{Float64, 3} ┐
├──────────────────────────────┴────────────────────────────────── dims ┐
  ↓ Dim_1 Sampled{Int64} Base.OneTo(10) ForwardOrdered Regular Points,
  → Dim_2 Sampled{Int64} Base.OneTo(20) ForwardOrdered Regular Points,
  ↗ Dim_3 Sampled{Int64} Base.OneTo(5) ForwardOrdered Regular Points
├───────────────────────────────────────────────────── loaded in memory ┤
  data size: 7.81 KB
└───────────────────────────────────────────────────────────────────────┘

julia> mapslices(mean, a, dims="Dim_1")
┌ 20×5 YAXArray{Union{Missing, Float64}, 2} ┐
├───────────────────────────────────────────┴───────────────────── dims ┐
  ↓ Dim_2 Sampled{Int64} Base.OneTo(20) ForwardOrdered Regular Points,
  → Dim_3 Sampled{Int64} Base.OneTo(5) ForwardOrdered Regular Points
├───────────────────────────────────────────────────── loaded in memory ┤
  data size: 800.0 bytes
└───────────────────────────────────────────────────────────────────────┘