Force to use the upstream version of OCaml 5.3.0

Author: dinosaure

.github/workflows/main.yml

@@ -18,6 +18,8 @@ jobs:
 # See jart/cosmopolitan#3
     - name: Fix binfmt and Cosmopolitan
       run: sudo sh -c "echo ':APE:M::MZqFpD::/bin/sh:' >/proc/sys/fs/binfmt_misc/register"
+    - name: Use the upstream version of OCaml 5.3.0
+      run: opam switch create 5.3.0
     - name: Pinning packages
       run: opam pin add -t -yn -vvv --kind=path --with-version=dev .
     - name: Install cosmopolitan/esperanto and dune