ci: use codecov coverage format

.github/workflows/ci.yml

@@ -312,7 +312,7 @@ jobs:
       - uses: codecov/codecov-action@v3
         if: steps.should-skip.outputs.skip != 'true'
         with:
-          file: coverage.lcov
+          file: coverage.json
           name: ${{ matrix.os }}
 
   emscripten:

noxfile.py

@@ -62,9 +62,9 @@ def coverage(session: nox.Session) -> None:
         "--package=pyo3-macros",
         "--package=pyo3-ffi",
         "report",
-        "--lcov",
+        "--codecov",
         "--output-path",
-        "coverage.lcov",
+        "coverage.json",
         external=True,
     )