Fixed CI

Author: ankane

.github/workflows/build.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: ocaml/setup-ocaml@v2
+      - uses: ocaml/setup-ocaml@v3
         with:
           ocaml-compiler: 5
       - uses: ankane/setup-postgres@v1