fbprophet -> prophet in doc/source/conf.py

[ascillitoe]

Change fbprophet to prophet in doc/source/conf.py. Following #627.

Fixes the following warning when building docs (without prophet installed):

WARNING: autodoc: failed to import module 'prophet' from module 'alibi_detect.od'; the following exception was raised:
No module named 'prophet'
WARNING: Failed guarded type import with ModuleNotFoundError("No module named 'prophet'")
WARNING: Cannot resolve forward reference in type annotations of "alibi_detect.utils.fetching.fetch_detector": name 'OutlierProphet' is not defined
WARNING: Cannot resolve forward reference in type annotations of "alibi_detect.utils.fetching.fetching.fetch_detector": name 'OutlierProphet' is not defined

[codecov-commenter]

Codecov Report

Merging #684 (71d4b82) into master (9a344ae) will decrease coverage by 0.08%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #684      +/-   ##
==========================================
- Coverage   79.76%   79.67%   -0.09%     
==========================================
  Files         131      131              
  Lines        9133     9133              
==========================================
- Hits         7285     7277       -8     
- Misses       1848     1856       +8     

Flag	Coverage Δ
macos-latest-3.10	?
ubuntu-latest-3.10	79.65% <ø> (ø)
ubuntu-latest-3.7	?
ubuntu-latest-3.8	?
ubuntu-latest-3.9	79.59% <ø> (ø)
windows-latest-3.9	76.88% <ø> (ø)

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Impacted Files	Coverage Δ
alibi_detect/saving/validators.py	76.92% <0.00%> (-13.47%)	⬇️
alibi_detect/utils/_types.py	95.23% <0.00%> (-4.77%)	⬇️