Fixed 3.9 build test

    - name: Build DeepChem

      run: |

        python -m pip install --upgrade pip

        pip install tensorflow'>=2.3,<2.4'

        pip install tensorflow'>=2.4'

        pip install -e .

    - name: Import checking

      run: python -c "import deepchem"

    conda create -y --name deepchem python=3.9 && \

    . /miniconda/etc/profile.d/conda.sh && \

    conda activate deepchem && \

    pip install tensorflow~=2.4 deepchem && \

    pip install tensorflow~=2.5 deepchem && \

    conda install -c conda-forge rdkit && \

    conda clean -afy && \

    rm -rf ~/.cache/pip

sphinx_rtd_theme>=0.5,<1

tensorflow>=2.4

transformers

torch==1.6.0

torch==1.8.0