chore(deps): update actions/cache action to v6 (#667)

Author: renovate[bot]

.github/workflows/links.yml

@@ -13,7 +13,7 @@ jobs:
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
 
-      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+      - uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: .lycheecache
           key: cache-lychee-${{ github.sha }}