DOC: fix SyntaxError in doc build on Windows

[simonjayhawkins]

i'm getting this error for most files during doc build on Windows...

>>>-------------------------------------------------------------------------
Exception in C:\Users\simon\OneDrive\code\pandas-simonjayhawkins\doc\source\development\contributing.rst at block ending on line None
Specify :okexcept: as an option in the ipython:: block to suppress this message
  File "<ipython-input-1-9cb881b1c9b0>", line 1
    os.chdir('C:\Users\simon\OneDrive\code\pandas-simonjayhawkins\doc')
            ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

<<<-------------------------------------------------------------------------

[codecov]

Codecov Report

Merging #26499 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #26499      +/-   ##
==========================================
- Coverage   91.75%   91.74%   -0.01%     
==========================================
  Files         174      174              
  Lines       50761    50761              
==========================================
- Hits        46575    46571       -4     
- Misses       4186     4190       +4

Flag	Coverage Δ
#multiple	90.25% <ø> (ø)	⬆️
#single	41.68% <ø> (-0.12%)	⬇️

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

---

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[codecov]

Codecov Report

Merging #26499 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #26499      +/-   ##
==========================================
- Coverage   91.75%   91.74%   -0.01%     
==========================================
  Files         174      174              
  Lines       50761    50761              
==========================================
- Hits        46575    46571       -4     
- Misses       4186     4190       +4

Flag	Coverage Δ
#multiple	90.25% <ø> (ø)	⬆️
#single	41.68% <ø> (-0.12%)	⬇️

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

---

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 6d2398a...6aee868. Read the comment docs.

[gfyoung]

Gotta love Windows...I thought we built the docs on Azure as well? If we don't, might want to consider doing that to protect against issues like these...