Move scikit-surprise and pymanopt from setup.py

[anargyri]

Description

• Remove scikit-surprise and pymanopt from setup.py because PyPI does not allow direct URLs.
• Update documentation to show how they can be pip installed manually.
• Update their pip installation in the nightly tests.

Related Issues

#1597

Checklist:

• I have followed the contribution guidelines and code style for this project.
• I have added tests covering my contributions.
• I have updated the documentation accordingly.
• This PR is being made to staging branch and not to main branch.

[codecov-commenter]

Codecov Report

Merging #1602 (4982381) into staging (7e52ebd) will decrease coverage by 3.66%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           staging    #1602      +/-   ##
===========================================
- Coverage    61.90%   58.23%   -3.67%     
===========================================
  Files           84       84              
  Lines         8462     8462              
===========================================
- Hits          5238     4928     -310     
- Misses        3224     3534     +310     

Flag	Coverage Δ
pr-gate	58.23% <ø> (-3.67%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
recommenders/models/rlrmc/RLRMCdataset.py	0.00% <0.00%> (-87.72%)	⬇️
recommenders/models/geoimc/geoimc_algorithm.py	7.24% <0.00%> (-78.27%)	⬇️
recommenders/models/rlrmc/conjugate_gradient_ms.py	0.00% <0.00%> (-69.50%)	⬇️
recommenders/models/geoimc/geoimc_predict.py	25.00% <0.00%> (-67.50%)	⬇️
recommenders/models/rlrmc/RLRMCalgorithm.py	0.00% <0.00%> (-66.93%)	⬇️
recommenders/models/geoimc/geoimc_utils.py	38.46% <0.00%> (-61.54%)	⬇️
recommenders/models/geoimc/geoimc_data.py	33.69% <0.00%> (-5.44%)	⬇️
recommenders/evaluation/spark_evaluation.py	87.05% <0.00%> (+0.44%)	⬆️

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