Upgrade @octokit/rest to 19.0.3

This upgrade contains changes to the API types which leads to several changes
around the code base handling the now more precise types.

Signed-off-by: Crevil <bjoern.soerensen@gmail.com>

packages/backend-common/package.json

@@ -42,7 +42,7 @@
     "@backstage/types": "^1.0.0",
     "@google-cloud/storage": "^6.0.0",
     "@manypkg/get-packages": "^1.1.3",
-    "@octokit/rest": "^18.5.3",
+    "@octokit/rest": "^19.0.3",
     "@types/cors": "^2.8.6",
     "@types/dockerode": "^3.3.0",
     "@types/express": "^4.17.6",