Closes #8649: Enable customization of configuration module using NETBOX_CONFIGURATION environment variable

.github/workflows/ci.yml

@@ -3,6 +3,8 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-latest
+    env:
+      NETBOX_CONFIGURATION: netbox.configuration_testing
     strategy:
       matrix:
         python-version: ['3.8', '3.9', '3.10']
@@ -57,7 +59,6 @@ jobs:
         python -m pip install --upgrade pip
         pip install -r requirements.txt
         pip install pycodestyle coverage
-        ln -s configuration.testing.py netbox/netbox/configuration.py
 
     - name: Build documentation
       run: mkdocs build