Swap out db-type and db-version for a more explicit db-image.

Author: johnbillion

.env.example

@@ -37,21 +37,14 @@ LOCAL_PHP_XDEBUG_MODE=develop,debug
 LOCAL_PHP_MEMCACHED=false
 
 ##
-# The database software to use.
+# The database image to use.
 #
-# Supported values are `mysql` and `mariadb`.
-##
-LOCAL_DB_TYPE=mysql
-
-##
-# The database version to use.
-#
-# Defaults to 8.0 with the assumption that LOCAL_DB_TYPE is set to `mysql` above.
+# Defaults to MySQL 8.0.
 #
 # When using `mysql`, see https://hub.docker.com/_/mysql for valid versions.
 # When using `mariadb`, see https://hub.docker.com/_/mariadb for valid versions.
 ##
-LOCAL_DB_VERSION=8.4
+LOCAL_DB_IMAGE=mysql:8.4
 
 # Whether or not to enable multisite.
 LOCAL_MULTISITE=false