Solution for old Dell printer drivers not working on Catalina with "can't be opened because ASpple cannot check it for malicious software"

Since upgrading to Catalina my Dell B1160w printer has not been working. I solved this problem today by using the "right click and Open With" method to ask the OS to prompt me whether to Open the program or not.

Steps:

1) Print something. The error appears. Click "Show in Finder"

2) In Finder, right click on the file that couldn't be opened (should be "rastertodell") and choose Open With->Terminal.app

3) When the OS prompts you if you want to open it, click "Open" then a terminal window appears. Quit Terminal.

4) Try to print again. You will get a similar error with a different file. Repeat steps 1..3 above for this file and the 3rd (should be "commandtodell" and then "libdscmssc.dylib")

5) Print!