Update transitive dependencies

I see a security vulnerability warning on Github. I hope that updating
transitive dependencies will silence the security warning.

I did `rm yarn.lock` followed by `yarn install`.

EDIT: OK, I found out what's causing the security warning. With
```
yarn list lodash
├─ bitcore-lib@0.13.19
│  └─ lodash@3.10.1
└─ lodash@4.17.15
```
gives us the hint that the outdated lodash comes from `bitcore-lib`
which in turn is required by the extremely outdated `activitystrea.ms`
package. I tried to update it's dependencies in my fork without success.
If we ever touch the activity pub implementation we might have to
maintain this package ourselves.

FYI: @Mastercuber

backend/package.json

@@ -61,7 +61,7 @@
     "dotenv": "~8.1.0",
     "express": "^4.17.1",
     "faker": "Marak/faker.js#master",
-    "graphql": "~14.4.2",
+    "graphql": "^14.5.0",
     "graphql-custom-directives": "~0.2.14",
     "graphql-iso-date": "~3.6.1",
     "graphql-middleware": "~3.0.5",