[CI] Update images to latest (#10)

* Update setup-ocaml to v3
* Add uninstall & clean step before rebuilding step

Author: dhil

.github/workflows/default.yml

@@ -15,8 +15,8 @@ jobs:
       fail-fast: false
       matrix:
         os:
-          - ubuntu-22.04
-          - macos-14
+          - ubuntu-latest
+          - macos-latest
         ocaml-compiler:
           - 5.1.1
           - 5.2.0
@@ -29,7 +29,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Use OCaml ${{ matrix.ocaml-compiler }}
-        uses: ocaml/setup-ocaml@v2
+        uses: ocaml/setup-ocaml@v3
         with:
           ocaml-compiler: ${{ matrix.ocaml-compiler }}
           opam-depext: false
@@ -50,6 +50,12 @@ jobs:
           opam exec -- dune build @runtest
         shell: bash
 
+      - name: Clean & uninstall
+        run: |
+          opam exec -- dune uninstall
+          opam exec -- dune clean
+        shell: bash
+
       - name: Rebuild library with UNIQUE_FIBERS
         run: |
           opam exec -- dune build