build(deps): update optuna requirement from <4.0.0,>=3.1.0 to >=3.1.0…

…,<5.0.0 (#1715)

Updates the requirements on [optuna](https://github.com/optuna/optuna)
to permit the latest version.

pyproject.toml

@@ -114,14 +114,14 @@ dependencies = [
 all_extras = [
   "cpflows",
   "matplotlib",
-  "optuna >=3.1.0,<4.0.0",
+  "optuna >=3.1.0,<5.0.0",
   "optuna-integration",
   "pytorch_optimizer >=2.5.1,<4.0.0",
   "statsmodels",
 ]
 
 tuning = [
-  "optuna >=3.1.0,<4.0.0",
+  "optuna >=3.1.0,<5.0.0",
   "optuna-integration",
   "statsmodels",
 ]