Bump actions/cache from 4 to 5 (#277)

Author: 4ever2

.github/workflows/build.yml

@@ -52,7 +52,7 @@ jobs:
       - run: sudo apt-get update
       - name: Restore opam cache
         id: opam-cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{github.workspace}}/_opam
           key: opam-${{env.OCAML_COMILER_VERSION}}-${{hashFiles('.github/coq-concert.opam.locked')}}

.github/workflows/refresh-cache.yml

@@ -21,7 +21,7 @@ jobs:
       - run: sudo apt-get update
       - name: Restore opam cache
         id: opam-cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{github.workspace}}/_opam
           fail-on-cache-miss: true