[PR #11804/bffff8cf backport][3.14] Bump blockbuster to 1.5.26

[patchback]

This is a backport of PR #11804 as merged into master (bffff8c).

What do these changes do?

Bump blockbuster to 1.5.26.
Needed because of false positives with Python 3.14.1t

Are there changes in behavior for the user?

No

[codspeed-hq]

CodSpeed Performance Report

Merging #11805 will not alter performance

_{Comparing patchback/backports/3.14/bffff8cfd3e9f1d078a4781912fc863c4d230a69/pr-11804 (be28b68) with 3.14 (b796fce)}

Summary

✅ 59 untouched

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.20%. Comparing base (b796fce) to head (be28b68).
⚠️ Report is 164 commits behind head on 3.14.

Additional details and impacted files

@@            Coverage Diff             @@
##             3.14   #11805      +/-   ##
==========================================
+ Coverage   97.65%   98.20%   +0.54%     
==========================================
  Files         128      128              
  Lines       44189    44189              
  Branches     2400     2400              
==========================================
+ Hits        43152    43394     +242     
+ Misses        828      613     -215     
+ Partials      209      182      -27     

Flag	Coverage Δ
CI-GHA	98.08% <ø> (+0.51%)	⬆️
OS-Linux	97.84% <ø> (+0.26%)	⬆️
OS-Windows	95.56% <ø> (?)
OS-macOS	97.09% <ø> (?)
Py-3.10.11	96.60% <ø> (?)
Py-3.10.19	97.10% <ø> (+0.14%)	⬆️
Py-3.11.14	97.35% <ø> (+0.13%)	⬆️
Py-3.11.9	96.85% <ø> (?)
Py-3.12.10	96.94% <ø> (?)
Py-3.12.12	97.44% <ø> (+0.13%)	⬆️
Py-3.13.9	97.67% <ø> (+0.37%)	⬆️
Py-3.14.0	97.65% <ø> (?)
Py-3.14.1t	96.73% <ø> (?)
Py-pypy3.11.13-7.3.20	96.92% <ø> (?)
VM-macos	97.09% <ø> (?)
VM-ubuntu	97.84% <ø> (+0.26%)	⬆️
VM-windows	95.56% <ø> (?)

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