Fix #1316: remove sample_dim docstring for condition.

[janfb]

In our current shape convention, condition does not have a sample_dim, but the docstring was saying something else.

fixes #1316

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.65%. Comparing base (d3f22b5) to head (c56056f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1338       +/-   ##
===========================================
- Coverage   89.40%   78.65%   -10.76%     
===========================================
  Files         118      118               
  Lines        8715     8722        +7     
===========================================
- Hits         7792     6860      -932     
- Misses        923     1862      +939     

Flag	Coverage Δ
unittests	78.65% <ø> (-10.76%)	⬇️

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

Files with missing lines	Coverage Δ
sbi/neural_nets/estimators/base.py	64.40% <ø> (ø)
sbi/neural_nets/estimators/nflows_flow.py	63.46% <ø> (ø)
sbi/neural_nets/estimators/zuko_flow.py	64.44% <ø> (ø)

... and 32 files with indirect coverage changes

[manuelgloeckler]

Look good. Just found the small typo (that hower already was there)