Clean dependencies; add extras feature (#451)

* clean dependencies; add extras feature

* add mpmath to test deps

pyproject.toml

@@ -5,48 +5,50 @@ build-backend = "setuptools.build_meta"
 [project]
 name = "pingouin"
 description = "Pingouin: statistical package for Python"
+readme = "README.rst"
+license = {text = "GPL-3.0"}
 authors = [
     {name = "Raphael Vallat", email = "[email protected]"},
 ]
-dependencies = [
-    "matplotlib",
-    "numpy",
-    "pandas>=1.5",
-    "pandas_flavor",
-    "scikit-learn>=1.2",
-    "scipy",
-    "seaborn",
-    "statsmodels",
-    "tabulate",
-]
-requires-python = ">=3.8"
-readme = "README.rst"
-license = {text = "GPL-3.0"}
 maintainers = [
     {name = "Raphael Vallat", email = "[email protected]"},
 ]
-dynamic = ["version"]
 classifiers = [
     "Intended Audience :: Science/Research",
     "Operating System :: MacOS",
     "Operating System :: POSIX",
     "Operating System :: Unix",
-    "Programming Language :: Python :: 3.10",
-    "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
     "Topic :: Scientific/Engineering :: Mathematics",
 ]
+dynamic = ["version"]
+requires-python = ">=3.8"
+dependencies = [
+    "matplotlib",
+    "numpy",
+    "pandas>=1.5",
+    "pandas_flavor",
+    "scikit-learn>=1.2",
+    "scipy",
+    "seaborn",
+    "statsmodels",
+    "tabulate",
+]
 
 [project.optional-dependencies]
+extras = [
+    "mpmath",
+]
 test = [
     "pytest>=6",
     "pytest-cov",
-    "codecov",
-    "openpyxl",
-    "mpmath",
     # Ensure coverage is new enough for `source_pkgs`.
     "coverage[toml]>=5.3",
+    "mpmath",
 ]
 docs = [
     "sphinx>7.0.0",