CLN: Remove unicode u string prefix in regexes

[simonjayhawkins]

xref #25725

[codecov]

Codecov Report

Merging #26433 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #26433      +/-   ##
==========================================
- Coverage   91.73%   91.72%   -0.01%     
==========================================
  Files         174      174              
  Lines       50741    50741              
==========================================
- Hits        46548    46543       -5     
- Misses       4193     4198       +5

Flag	Coverage Δ
#multiple	90.23% <ø> (ø)	⬆️
#single	41.69% <ø> (-0.11%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	78.94% <0%> (-10.53%)	⬇️
pandas/core/frame.py	97.02% <0%> (-0.12%)	⬇️
pandas/util/testing.py	90.6% <0%> (-0.11%)	⬇️

---

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[codecov]

Codecov Report

Merging #26433 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #26433      +/-   ##
==========================================
- Coverage   91.73%   91.72%   -0.01%     
==========================================
  Files         174      174              
  Lines       50741    50741              
==========================================
- Hits        46548    46543       -5     
- Misses       4193     4198       +5

Flag	Coverage Δ
#multiple	90.23% <ø> (ø)	⬆️
#single	41.69% <ø> (-0.11%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	78.94% <0%> (-10.53%)	⬇️
pandas/core/frame.py	97.02% <0%> (-0.12%)	⬇️
pandas/util/testing.py	90.6% <0%> (-0.11%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1263e1a...4f1c13b. Read the comment docs.