allow to configure database version via ENV var (#2055)

config/packages/doctrine.yaml

@@ -4,6 +4,7 @@ parameters:
     # environment variables are not available yet.
     # You should not need to change this value.
     env(DATABASE_URL): ''
+    env(DATABASE_VERSION): ~
 
 doctrine:
     dbal:
@@ -14,7 +15,7 @@ doctrine:
                 driver: 'pdo_mysql'
                 # this setting prevents automatic database detection and finds a lot of false-negatives on doctrine:migrations:diff
                 # for null columns with MariaDB. Each migration tries to convert EVERY nullable column.
-                # server_version: '5.7'
+                server_version: '%env(string:DATABASE_VERSION)%'
                 charset: utf8mb4
                 default_table_options:
                     charset: utf8mb4