fix: update backend url everywhere

Author: bodobraegger

.env.example

@@ -4,4 +4,4 @@ REACT_APP_VERSION=1.0.0
 REACT_APP_NAME=$npm_package_name
 
 REACT_APP_PUBLIC_URL=/
-BACKEND_URL=https://backend.thilo.ch/
+BACKEND_URL=https://api.thilo.scouts.ch/

.github/workflows/deploy.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     env:
       REACT_APP_PUBLIC_URL: /
-      BACKEND_URL: https://thilo-backend.herokuapp.com
+      BACKEND_URL: https://api.thilo.scouts.ch/
 
     steps:
       - uses: actions/checkout@v4