Revert "try to set up nightly builds"

This reverts commit cbf24a5.

Author: Jérôme FERET

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -34,7 +34,7 @@ jobs:
           - labltk
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -69,7 +69,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -98,7 +98,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -138,7 +138,7 @@ jobs:
     runs-on: macos-15
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -168,7 +168,7 @@ jobs:
     runs-on: windows-2022
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
         with:
@@ -201,7 +201,7 @@ jobs:
 #    timeout-minutes: 75
 #    runs-on: ubuntu-latest
 #    steps:
-#    - uses: actions/checkout@v5
+#    - uses: actions/checkout@v6
 #    - uses: actions/setup-node@v4
 #      with:
 #        node-version: lts/*
@@ -270,7 +270,7 @@ jobs:
 #        deploy-name: [doc, online-ui, linux, macos, windows]
 #    steps:
 #      - name: Checkout
-#        uses: actions/checkout@v5
+#        uses: actions/checkout@v6
 #      - name: Download artifact
 #        uses: actions/download-artifact@v4
 #        with: