chore: change DEBUG namespace to loopback:mixin:calculated

Author: Tom Kirkpatrick

README.md

@@ -125,5 +125,5 @@ DEBUGGING
 Run with debugging output on:
 
 ```bash
-  DEBUG='loopback-ds-calculated-mixin' npm test
+  DEBUG='loopback:mixin:calculated' npm test
 ```

lib/calculated.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const debug = require('debug')('loopback-ds-calculated-mixin')
+const debug = require('debug')('loopback:mixin:calculated')
 const _ = require('lodash')
 const Promise = require('bluebird')