In my app package.json 

...
"dependencies": {
		"vibe-d": ">=0.7.16",
		"ddbc": ">=0.2.9"
	},
...

ddbc should be using the configuration 

"configurations":[
...
{ 
  ...
  "name": PGSQL,
  "versions": ["USE_PGSQL"],
  ...
},
...

How do I configure my apps package.json to force the use of USE_PGSQL?

Thanks,
Arjan