chore(project): bump diagram-js dependency

Adds support for reacting to element.contextmenu.

Related to #750

package-lock.json

@@ -1651,9 +1651,9 @@
       "dev": true
     },
     "diagram-js": {
-      "version": "0.27.2",
-      "resolved": "https://registry.npmjs.org/diagram-js/-/diagram-js-0.27.2.tgz",
-      "integrity": "sha512-fX3o7kSZmc2ONWxv/JD+7+1yhGbYMuVlfUweQ4VwjVXweJxH+PJ3vscOijXOt92/q9R7nDmh3hdbuL++C86/GA==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/diagram-js/-/diagram-js-0.28.0.tgz",
+      "integrity": "sha512-aS/hbQrNWMqoIYJqi06FkaMvj7edH+xj625NPgxpvpZY2jFRHjGSKViwNIpBCVK0QfQAWdQNr8xfddoJax903w==",
       "requires": {
         "didi": "0.1.1",
         "hammerjs": "2.0.8",

package.json

@@ -76,7 +76,7 @@
   },
   "dependencies": {
     "bpmn-moddle": "^2.1.0",
-    "diagram-js": "^0.27.2",
+    "diagram-js": "^0.28.0",
     "diagram-js-direct-editing": "^0.22.0",
     "ids": "^0.2.0",
     "inherits": "^2.0.1",