chore(ci): Collect coverage from parallel test workers

Configure coverage.py for multiprocessing so Django's parallel test
workers are included in the coverage data.

Move coverage source and report settings into pyproject.toml,
and combine per-process coverage data before generating the report.

Fixes #22118

.github/workflows/ci.yml

@@ -122,12 +122,12 @@ jobs:
 
     - name: Run tests with coverage
       if: ${{ matrix.coverage }}
-      run: >-
-        coverage run --source="netbox/"
-        netbox/manage.py test netbox/ --parallel
+      run: coverage run netbox/manage.py test netbox/ --parallel
+
+    - name: Combine coverage data
+      if: ${{ matrix.coverage }}
+      run: coverage combine
 
     - name: Show coverage report
       if: ${{ matrix.coverage }}
-      run: >-
-        coverage report --skip-covered
-        --omit '*/migrations/*,*/tests/*'
+      run: coverage report

pyproject.toml

@@ -26,6 +26,19 @@ Documentation = "https://netboxlabs.com/docs/netbox/"
 Source = "https://github.com/netbox-community/netbox"
 Issues = "https://github.com/netbox-community/netbox/issues"
 
+[tool.coverage.run]
+source = ["netbox/"]
+concurrency = ["multiprocessing"]
+parallel = true
+sigterm = true
+
+[tool.coverage.report]
+skip_covered = true
+omit = [
+    "*/migrations/*",
+    "*/tests/*",
+]
+
 [tool.pyright]
 include = ["netbox"]
 exclude = [