Note: Atom 1.50.0 is now in stable, so the workaround below should not be necessary anymore.
After upgrading my laptop to Linux Mint 20, I found myself unable to install the provided .deb installation file without messing with python dependencies. I did some research, and found that removing the python dependency from the .deb package is all you need to do.
With these few steps, you can do it yourself. (source)
dpkg -x atom-amd64.deb atom-src dpkg -e atom-amd64.deb atom-src/DEBIAN # Remove python dependency in atom-src/DEBIAN/control dpkg -b atom-src/ new-atom-amd64.deb sudo dpkg -i new-atom-amd64.deb
Note that this will be fixed in the near future. If you want to use a stable version (1.50.0), wait a little, if you are okay with using a beta version for some time, install the latest beta v1.50.0-beta0 (2020-07-14), which has the fix included (download link).
If you don’t feel like using the beta nor the aforementioned steps, drop me a line and I’ll send you the modified package (~125 MB).