Update deprecated phinx config (#808)

Error message when running phinx commands:
```
Deprecated: default_database in the config has been deprecated since 0.12, use default_environment instead. in /var/www/html/vendor/robmorgan/phinx/src/Phinx/Config/Config.php on line 223
```

Author: pylipp

phinx.yml

@@ -11,7 +11,7 @@ paths:
     migrations: '%%PHINX_CONFIG_DIR%%/db/migrations'
 environments:
     default_migration_table: phinxlog
-    default_database: development
+    default_environment: development
     development:
         adapter: mysql
         host: 127.0.0.1