No ambiente conda:
conda install -c conda-forge gdal=2.2.1
Em django settings.py:
GDAL_LIBRARY_PATH = '<HOME>/anaconda3/envs/<env_name>/lib/libgdal.so'
conda install -c conda-forge gdal=2.2.1
GDAL_LIBRARY_PATH = '<HOME>/anaconda3/envs/<env_name>/lib/libgdal.so'