Conda install script is broken

## 🐛 Bug

The documentation specifies to install deepchem and its dependencies with conda to run `source scripts/install_deepchem_conda.sh 3.8 gpu`. However, it does not install correctly and does not raise any failures.

## To Reproduce

Steps to reproduce the behavior:

1. git clone https://github.com/deepchem/deepchem.git
2. cd deepchem
3. source scripts/install_deepchem_conda.sh 3.8 gpu

## Expected behavior

A conda environment should be created according to the requested specifications. Currently it seems to try to install tensorflow, jax and pytorch into the same environment, which doesn't work. An option similar to the pip installation which allows the user to specify which framework to install should be available. For example `./install_deepchem_conda.sh pytorch gpu`.