Bump for 4.0.0b2

[michaelosthege]

I fixed two links in the readme that were broken.

⚠ The links in the readme point to a mix between v3 and v4 documentation, but for the ones I changed I didn't find good v3 targets.

[codecov]

Codecov Report

Merging #5348 (35479eb) into main (18e5e28) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5348      +/-   ##
==========================================
- Coverage   80.21%   80.20%   -0.02%     
==========================================
  Files          89       89              
  Lines       14845    14856      +11     
==========================================
+ Hits        11908    11915       +7     
- Misses       2937     2941       +4     

Impacted Files	Coverage Δ
pymc/__init__.py	100.00% <100.00%> (ø)
pymc/parallel_sampling.py	86.37% <0.00%> (-1.33%)	⬇️
pymc/data.py	80.67% <0.00%> (-0.09%)	⬇️
pymc/model.py	84.22% <0.00%> (+0.06%)	⬆️
pymc/sampling.py	86.41% <0.00%> (+0.14%)	⬆️

[OriolAbril]

looks like I was too late. I pushed to https://github.com/pymc-devs/pymc/tree/bump-4b2. I rerun the notebooks and fixed the link in the readme pointing to pymc examples. I can try to rebase and send a new PR tomorrow