Update tests to BlockArrays.jl v1.8

[mtfishman]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.85%. Comparing base (99413d9) to head (5ffae36).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #186      +/-   ##
==========================================
- Coverage   72.00%   71.85%   -0.15%     
==========================================
  Files          37       37              
  Lines        2029     2029              
==========================================
- Hits         1461     1458       -3     
- Misses        568      571       +3     

Flag	Coverage Δ
docs	5.95% <ø> (ø)

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