fix: app/package.json & app/package-lock.json to reduce vulnerabilities (#49)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AXIOS-1579269

Co-authored-by: Mathieu Brunot <[email protected]>

Author: snyk-bot

app/package-lock.json

@@ -33,7 +33,7 @@
     "@fortawesome/fontawesome-svg-core": "^1.2.36",
     "@fortawesome/free-solid-svg-icons": "^5.15.4",
     "@fortawesome/vue-fontawesome": "^0.1.9",
-    "axios": "^0.21.1",
+    "axios": "^0.21.3",
     "buefy": "^0.9.8",
     "dotenv-webpack": "^2.0.0",
     "vue": "^2.6.11",