Bump ocaml/setup-ocaml from 2 to 3 (#17)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Check out library
         uses: actions/checkout@v4
       - name: Install ocaml and opam
-        uses: ocaml/setup-ocaml@v2
+        uses: ocaml/setup-ocaml@v3
         with:
           ocaml-compiler: 4.14.1
       - name: Install required libraries