pin to chart.js 2.7.x

Author: sgratzl

README.md

@@ -1,7 +1,7 @@
 # Chart.js Box and Violin Plot
 [![datavisyn][datavisyn-image]][datavisyn-url] [![NPM Package][npm-image]][npm-url] [![CircleCI][circleci-image]][circleci-url]
 
-Chart.js module for charting box and violin plots
+Chart.js module for charting box and violin plots. **Works only with Chart.js ~2.7.x**
 
 ![Box Plot](https://user-images.githubusercontent.com/4129778/42724341-9a6ec554-8770-11e8-99b5-626e34dafdb3.png)
 ![Violin Plot](https://user-images.githubusercontent.com/4129778/42724342-9a8dbb58-8770-11e8-9a30-3e69d07d3b79.png)

package-lock.json

@@ -20,7 +20,7 @@
     "src/**/*.js"
   ],
   "dependencies": {
-    "chart.js": "^2.7.3",
+    "chart.js": "~2.7.3",
     "@sgratzl/science": "^2.0.0"
   },
   "devDependencies": {