Switch to log-acqfs (emdgroup#326)

This PR changes the default acquisition function from `qEI` to
`qLogEI`, which improves numerical stability and also avoids the warning
thrown in `botorch>=0.11.3`.

CHANGELOG.md

@@ -59,6 +59,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   two fixed low and high dimensional prior regimes
 - The previous default kernel factory has been renamed to `EDBOKernelFactory` and now
   fully reflects the original logic
+- The default acquisition function has been changed from "qEI" to "qLogEI" for improved
+  numerical stability
 
 ### Removed
 - Support for Python 3.9 removed due to new [BoTorch requirements](https://github.com/pytorch/botorch/pull/2293) 

baybe/recommenders/pure/bayesian/base.py

@@ -5,7 +5,7 @@
 import pandas as pd
 from attrs import define, field
 
-from baybe.acquisition.acqfs import qExpectedImprovement
+from baybe.acquisition.acqfs import qLogExpectedImprovement
 from baybe.acquisition.base import AcquisitionFunction
 from baybe.acquisition.utils import convert_acqf
 from baybe.exceptions import DeprecationError
@@ -25,7 +25,7 @@ class BayesianRecommender(PureRecommender, ABC):
     """The used surrogate model."""
 
     acquisition_function: AcquisitionFunction = field(
-        converter=convert_acqf, factory=qExpectedImprovement
+        converter=convert_acqf, factory=qLogExpectedImprovement
     )
     """The used acquisition function class."""