github/workflows: set the codecov token

The codecov-action v4 requires a token.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>

Author: jluebbe

.github/workflows/reusable-unit-tests.yml

@@ -68,3 +68,5 @@ jobs:
         pip install rstcheck
         rstcheck --ignore-languages=bash --report-level=WARNING README.rst
     - uses: codecov/codecov-action@v4
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}