Fix workflow

Author: edwinans

.github/workflows/workflow.yml

@@ -7,15 +7,7 @@ on:
 
 jobs:
   build:
-    strategy:
-      fail-fast: false
-      matrix:
-        os:
-          - ubuntu-latest
-        ocaml-compiler:
-          - 5.1.x
-
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
 
     steps:
       - run: |
@@ -24,10 +16,10 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Use OCaml ${{ matrix.ocaml-compiler }}
-        uses: ocaml/setup-ocaml@v2
+      - name: Setup OCaml
+        uses: ocaml/setup-ocaml@v3
         with:
-          ocaml-compiler: ${{ matrix.ocaml-compiler }}
+          ocaml-compiler: 5
 
       - run: opam install . --deps-only