Remove unnecessary obstore import

[maxrjones]

Call store.get_range_async(...) rather than obstore.get_range_async(store, ...)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.34%. Comparing base (c689197) to head (a015bba).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #599      +/-   ##
===========================================
- Coverage    89.34%   89.34%   -0.01%     
===========================================
  Files           34       34              
  Lines         1943     1942       -1     
===========================================
- Hits          1736     1735       -1     
  Misses         207      207              

Files with missing lines	Coverage Δ
virtualizarr/manifests/store.py	91.97% <100.00%> (-0.05%)	⬇️

🚀 New features to boost your workflow:

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