ci: run codecov directly instead of via GitHub Action

.github/workflows/run_tests.yml

@@ -26,12 +26,11 @@ jobs:
           python3 -m pip install ".[dev]"
 
       - name: Run tests
-        run:  |
+        run: |
           source ./environment.sh
           source venv/bin/activate
           make test
 
       - name: Upload results to Codecov
-        uses: codecov/codecov-action@v4
-        with:
-          token: ${{ secrets.CODECOV_TOKEN }}
+        run: |
+          codecov -t ${{ secrets.CODECOV_TOKEN }}

Makefile

@@ -1,6 +1,6 @@
 .PHONY: test format clean serve_docs
 test:
-	python3 -m pytest --cov-report json
+	python3 -m pytest --cov
 
 format:
 	python3 -m black .

pyproject.toml

@@ -20,6 +20,7 @@ requires-python = ">=3.8"
 dev = [
   "pytest",
   "pytest-cov",
+  "codecov",
   "ruff",
   "mkdocs-material",
   "amaranth_boards@git+https://github.com/amaranth-lang/amaranth-boards"