Simplify sed command in Dockerfile

Author: rwest

Dockerfile

@@ -89,6 +89,6 @@ RUN rm -rf examples/rmg/rms_constant_V/* && \
     git checkout -- examples/rmg/rms_constant_V/
 
 # when running this image, open an interactive bash terminal inside the rmg_env conda environment
-RUN sed -i '/\. \/opt\/conda\/etc\/profile.d\/conda.sh && conda activate base/c\. /opt/conda/etc/profile.d/conda.sh && conda activate rmg_env' ~/.bashrc
+RUN sed -i 's/conda activate base/conda activate rmg_env/' ~/.bashrc
 ENTRYPOINT ["/bin/bash", "--login"]