fix: expand coverage to full malariagen_data package and update codecov action

- Changed --cov target from malariagen_data/anoph to malariagen_data so
  coverage measurement includes all root-level modules (ag3.py, af1.py,
  plasmodium.py, veff.py, util.py, etc.) that were previously excluded
- Updated codecov/codecov-action from v3 to v4 for security fixes

Closes #1301

Author: kunal-10-cloud

.github/workflows/coverage.yml

@@ -21,10 +21,10 @@ jobs:
           python-version: "3.12"
 
       - name: Run unit tests with coverage
-        run: poetry run pytest -v tests --ignore tests/integration --cov malariagen_data/anoph --cov-report=xml
+        run: poetry run pytest -v tests --ignore tests/integration --cov malariagen_data --cov-report=xml
 
       - name: Upload coverage report
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           files: ./coverage.xml
           verbose: true