Update actions/cache action to v5

Author: renovate[bot]

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Install devenv.sh
         run: nix profile add nixpkgs#devenv
       - name: Cache dependencies
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: |
             ~/.cache/bundle

.github/workflows/deploy.yml

@@ -30,7 +30,7 @@ jobs:
         with:
           ref: ${{ env.GIT_REF }}
       - name: Cache dependencies
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: |
             ~/.cache/bundle