Update codecov action to v4

Author: pool2win

.github/workflows/rust.yml

@@ -78,7 +78,7 @@ jobs:
         run: cargo tarpaulin --out xml --target-dir target --skip-clean --release
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: cobertura.xml