add cypress/browsers:node14.16.0-chrome89-ff78

[sl4mmy]

Chrome 89 is now in the stable channel, and FireFox 78 is the current extended support release.

Signed-off-by: Kent R. Spillner [email protected]

[CLAassistant]

All committers have signed the CLA.

[jordanpowell88]

Going to close this image as it's over a year old. If you still need this image you can generate a new one using one of these scripts: https://github.com/cypress-io/cypress-docker-images/blob/master/package.json#L12-L14