Update actions/cache action to v6

Author: renovate[bot]

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
 
       - name: Cache cargo registry
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cargo/registry