Fix setting zero dimensional block

[mtfishman]

Fixes #27.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 27.25%. Comparing base (004403d) to head (f9d4c21).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ksparsearrayinterface/blocksparsearrayinterface.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #28   +/-   ##
=======================================
  Coverage   27.25%   27.25%           
=======================================
  Files          29       29           
  Lines         987      987           
=======================================
  Hits          269      269           
  Misses        718      718           

Flag	Coverage Δ
docs	26.80% <0.00%> (ø)

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