[MNT] remove unused dependencies from pyproject.toml (#602)

removes unused dependencies from `pyproject.toml`, and moves those used
only in notebooks to a new `notebooks` depset:

* `tensorboard`
* `protobuf`
* `PyYAML`
* `matplotlib`
* `ipywidgets`
* `fsspec`

Author: fkiraly

pyproject.toml

@@ -47,15 +47,9 @@ dependencies = [
     "scipy>=1.8,<2.0",
     "omegaconf>=2.3.0",
     "torchmetrics>=0.10.0,<1.7.0",
-    "tensorboard>2.2.0,!=2.5.0",
-    "protobuf>=3.20.0,<5.30.0",
     "pytorch-tabnet==4.1",
-    "PyYAML>=5.4,<6.1.0",
-    "matplotlib>3.1",
-    "ipywidgets",
     "einops>=0.6.0,<0.8.0",
-    "fsspec>=2022.5.0,<2024.4.0; python_version == '3.8'",
-    "rich",
+    "rich>=11.0.0",
     "scikit-base",
 ]
 
@@ -81,6 +75,11 @@ extra = [
     "captum>=0.5.0,<0.8.0",
 ]
 
+notebooks = [
+    "ipywidgets",
+    "matplotlib>3.1",
+]
+
 
 [project.urls]
 Homepage = "https://github.com/pytorch-tabular/pytorch_tabular"