Bump ocaml/setup-ocaml from 2 to 3

Bumps [ocaml/setup-ocaml](https://github.com/ocaml/setup-ocaml) from 2 to 3.
- [Release notes](https://github.com/ocaml/setup-ocaml/releases)
- [Changelog](https://github.com/ocaml/setup-ocaml/blob/master/CHANGELOG.md)
- [Commits](ocaml/setup-ocaml@v2...v3)

---
updated-dependencies:
- dependency-name: ocaml/setup-ocaml
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/coq-windows.yml

@@ -41,7 +41,7 @@ jobs:
       with:
         python-version: 3.x
     - name: Set up OCaml
-      uses: ocaml/setup-ocaml@v2
+      uses: ocaml/setup-ocaml@v3
       with:
         ocaml-compiler: 4.13.1
         opam-repositories: |