PHP 7.4 (again), Ubuntu 20.04
Fixed
- Upgrade PHP to 7.4 again (but stay with Ubuntu base O/S)
- Upgrade Ubuntu to 20.04
- Upgrade Composer to 2
- Switch from fxp's composer-asset-plugin to asset-packagist
- Stop including syslog and Logentries-related files
- Stop installing/using runny (since we don't log to syslog anymore)