[CI] [Windows] Bump to OCaml 4.13.1 (#1936)

In preparation for setup-ocaml@v3

Author: JasonGross

.github/workflows/coq-windows.yml

@@ -43,7 +43,7 @@ jobs:
     - name: Set up OCaml
       uses: ocaml/setup-ocaml@v2
       with:
-        ocaml-compiler: 4.11.1
+        ocaml-compiler: 4.13.1
         opam-repositories: |
           opam-repository-mingw: https://github.com/ocaml-opam/opam-repository-mingw.git#sunset
           default: https://github.com/ocaml/opam-repository.git