Update conda install instructions (#918)

Until now, the conda install instructions relied on the environment.yml
in this repo. However, this file was rarely if ever updated, so it's
actually not a good idea to use it. Furthermore, for the purpose of
developing on skorch, there is no good reason why exactly those versions
should be used, as they will likely differ from what is run on CI
anyway. Therefore, this PR removes the environment.yml and updates the
conda install instructions not to rely on it.

One further minor change is not to install cudatoolkit but instead
pytorch-cuda, which is what is recommended on pytorch.org.

README.rst

@@ -182,8 +182,10 @@ To install skorch from source using conda, proceed as follows:
 
     git clone https://github.com/skorch-dev/skorch.git
     cd skorch
-    conda env create
-    conda activate skorch
+    conda create -n skorch-env python=3.10
+    conda activate skorch-env
+    conda install -c pytorch pytorch
+    python -m pip install -r requirements.txt
     python -m pip install .
 
 If you want to help developing, run:
@@ -192,13 +194,18 @@ If you want to help developing, run:
 
     git clone https://github.com/skorch-dev/skorch.git
     cd skorch
-    conda env create
-    conda activate skorch
+    conda create -n skorch-env python=3.10
+    conda activate skorch-env
+    conda install -c pytorch pytorch
+    python -m pip install -r requirements.txt
+    python -m pip install -r requirements-dev.txt
     python -m pip install -e .
 
     py.test  # unit tests
     pylint skorch  # static code checks
 
+You may adjust the Python version to any of the supported Python versions.
+
 Using pip
 ---------
 
@@ -251,7 +258,7 @@ In general, running this to install PyTorch should work:
 .. code:: bash
 
     # using conda:
-    conda install pytorch cudatoolkit -c pytorch
+    conda install pytorch pytorch-cuda -c pytorch
     # using pip
     python -m pip install torch
 

docs/user/installation.rst

@@ -35,8 +35,10 @@ If you just want to use skorch, use:
 
     git clone https://github.com/skorch-dev/skorch.git
     cd skorch
-    conda env create
-    conda activate skorch
+    conda create -n skorch-env python=3.10
+    conda activate skorch-env
+    # install pytorch version for your system (see below)
+    python -m pip install -r requirements.txt
     python -m pip install .
 
 If you want to help developing, run:
@@ -45,13 +47,19 @@ If you want to help developing, run:
 
     git clone https://github.com/skorch-dev/skorch.git
     cd skorch
-    conda env create
-    conda activate skorch
+    conda create -n skorch-env python==3.10
+    conda activate skorch-env
+    # install pytorch version for your system (see below)
+    python -m pip install -r requirements.txt
+    python -m pip install -r requirements-dev.txt
     python -m pip install -e .
 
     py.test  # unit tests
     pylint skorch  # static code checks
 
+You may adjust the Python version to any of the supported Python versions, i.e.
+Python 3.7 or higher.
+
 Using pip
 ^^^^^^^^^
 
@@ -99,12 +107,11 @@ However, that doesn't mean that older versions don't work, just that
 they aren't tested. Since skorch mostly relies on the stable part of
 the PyTorch API, older PyTorch versions should work fine.
 
-In general, running this to install PyTorch should work (assuming CUDA
-11.1):
+In general, running this to install PyTorch should work:
 
 .. code:: bash
 
     # using conda:
-    conda install pytorch cudatoolkit==11.1 -c pytorch
+    conda install pytorch pytorch-cuda -c pytorch
     # using pip
     python -m pip install torch