Fix open dataset with length 1 dim

[danlooo]

This PR aims to Fix opening a Dataset with an YAXArray having a integer dimension of length 1. Thanks, @meggart, for the hint!

using YAXArrays
using Zarr
a = YAXArray(ones(5, 1))
ds = Dataset(layer=a)
path = tempname() * ".zarr"
savedataset(ds; path=path)
ds2 = open_dataset(path)

results in error:

ERROR: BoundsError: attempt to access 0-element Vector{Int64} at index [1]
Stacktrace:
  [1] throw_boundserror(A::Vector{Int64}, I::Tuple{Int64})
    @ Base ./essentials.jl:14
  [2] getindex
    @ ./essentials.jl:916 [inlined]
  [3] testrange(x::Vector{Int64})
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:321
  [4] toaxis(dimname::String, g::ZarrExt.ZarrDataset, offs::Int64, len::Int64)
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:294
  [5] (::YAXArrays.Datasets.var"#44#46"{ZarrExt.ZarrDataset})(d::Tuple{String, Int64, Int64})
    @ YAXArrays.Datasets ./none:0
  [6] iterate
    @ ./generator.jl:48 [inlined]
  [7] grow_to!(dest::Dict{String, @NamedTuple{…}}, itr::Base.Generator{Set{…}, YAXArrays.Datasets.var"#44#46"{…}}, st::Int64)
    @ Base ./abstractdict.jl:606
  [8] grow_to!(dest::Dict{Any, Any}, itr::Base.Generator{Set{Tuple{…}}, YAXArrays.Datasets.var"#44#46"{ZarrExt.ZarrDataset}})
    @ Base ./abstractdict.jl:602
  [9] dict_with_eltype
    @ ./abstractdict.jl:641 [inlined]
 [10] Dict
    @ ./dict.jl:117 [inlined]
 [11] collectdims(g::ZarrExt.ZarrDataset)
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:269
 [12] (::YAXArrays.Datasets.var"#67#75"{Tuple{}})(g::ZarrExt.ZarrDataset)
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:435
 [13] open_dataset_handle(f::YAXArrays.Datasets.var"#67#75"{Tuple{}}, ds::ZarrExt.ZarrDataset)
    @ YAXArrayBase ~/.julia/packages/YAXArrayBase/M48vP/src/datasets/datasetinterface.jl:23
 [14] open_dataset(g::String; skip_keys::Tuple{}, driver::Symbol)
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:433
 [15] open_dataset(g::String)
    @ YAXArrays.Datasets ~/.julia/packages/YAXArrays/x5iTf/src/DatasetAPI/Datasets.jl:430
 [16] top-level scope
    @ REPL[7]:1
Some type information was truncated. Use `show(err)` to see complete types.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.81%. Comparing base (cc966fd) to head (87d18cb).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #504      +/-   ##
==========================================
+ Coverage   68.79%   68.81%   +0.01%     
==========================================
  Files          14       14              
  Lines        2096     2097       +1     
==========================================
+ Hits         1442     1443       +1     
  Misses        654      654              

Files with missing lines	Coverage Δ
src/DatasetAPI/Datasets.jl	85.76% <100.00%> (+0.02%)	⬆️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.