Have continuous integration test several databases

[ChristianMurphy]

Currently CI tests only HSQL db, it would be good to test on more than one commonly used open source database to ensure compatibility.

Previously CI also tested with MariaDB

uPortal-start/.travis.yml

Lines 35 to 45 in 98f803d

	if [ "$DB" = 'mariadb' ]; then
	echo mysql conf `ls -la /etc/mysql/*`
	sudo ls -l /etc/mysql/my.cnf
	sudo find / -name "mariadb.cnf" -exec ls -l \{\} \;
	sudo find / -name "my.cnf" -exec ls -l \{\} \;
	echo "show my.cnf"
	sudo find / -name "my.cnf" -exec sudo cat \{\} \;
	echo "show mariadb.cnf"
	sudo find / -name "mariadb.cnf" -exec sudo cat \{\} \;
	sudo ls -l /var/lib/mysql/
	fi

This didn't make the initial migration from Travis CI to GitHub actions, but could likely be adapted.

PostreSQL could be another good database to check with.