⬆️ deps: Update actions/checkout action to v6 (#218)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/rcalc-test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Dependencies
         run: sudo apt update && sudo apt install -y libtinfo5
       - name: Update rust toolchain