fix: support for Zarr V2 zstd encoded data created with numcodecs < 0.13

[LDeakin]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.

Project coverage is 81.61%. Comparing base (15187a0) to head (a0f605f).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
zarrs_metadata/src/v2/array/codec/zstd.rs	75.00%	2 Missing ⚠️
zarrs_metadata/src/v2_to_v3.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #121   +/-   ##
=======================================
  Coverage   81.61%   81.61%           
=======================================
  Files         166      167    +1     
  Lines       23825    23842   +17     
=======================================
+ Hits        19444    19458   +14     
- Misses       4381     4384    +3     

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