Fix Docker build

package-lock.json

@@ -66,6 +66,15 @@
         "@types/node": "*"
       }
     },
+    "@types/ws": {
+      "version": "7.2.7",
+      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-7.2.7.tgz",
+      "integrity": "sha512-UUFC/xxqFLP17hTva8/lVT0SybLUrfSD9c+iapKb0fEiC8uoDbA+xuZ3pAN603eW+bY8ebSMLm9jXdIPnD0ZgA==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
     "@typescript-eslint/eslint-plugin": {
       "version": "2.13.0",
       "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-2.13.0.tgz",
@@ -2094,4 +2103,4 @@
       }
     }
   }
-}
+}

package.json

@@ -39,6 +39,7 @@
   "devDependencies": {
     "@types/node": "^12.12.21",
     "@types/node-schedule": "^1.3.0",
+    "@types/ws": "^7.2.7",
     "@typescript-eslint/eslint-plugin": "^2.13.0",
     "@typescript-eslint/parser": "^2.13.0",
     "eslint": "^6.8.0",
@@ -53,4 +54,4 @@
   "eslintIgnore": [
     "**/*.js"
   ]
-}
+}