Fix sqlite store in 2.x

[dstansby]

This is a minimal attempt to fix the failing sqlite tests on the 2.x branch

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.95%. Comparing base (2bf7e45) to head (7498427).
Report is 19 commits behind head on support/v2.

Additional details and impacted files

@@             Coverage Diff             @@
##           support/v2    #2880   +/-   ##
===========================================
  Coverage       99.95%   99.95%           
===========================================
  Files              38       38           
  Lines           14672    14680    +8     
===========================================
+ Hits            14666    14674    +8     
  Misses              6        6           

Files with missing lines	Coverage Δ
zarr/_storage/v3.py	100.00% <100.00%> (ø)
zarr/storage.py	99.77% <100.00%> (ø)

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