Update GitHub Actions

Signed-off-by: Sora Morimoto <sora@morimoto.io>

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly

.github/workflows/build.yml

@@ -14,23 +14,22 @@ jobs:
           - ubuntu-latest
           - windows-latest
         ocaml-compiler:
-          - 4.10.x
-          - 4.11.x
-          - 4.12.x
+          - "4.10"
+          - "4.11"
+          - "4.12"
 
     runs-on: ${{ matrix.os }}
 
     steps:
-      - name: Checkout code
-        uses: actions/checkout@v3
+      - name: Checkout tree
+        uses: actions/checkout@v4
 
-      - name: Use OCaml ${{ matrix.ocaml-compiler }}
+      - name: Set-up OCaml
         uses: ocaml/setup-ocaml@v2
         with:
           ocaml-compiler: ${{ matrix.ocaml-compiler }}
+          allow-prerelease-opam: true
 
-      - name: Install dependencies
-        run: opam install --deps-only .
+      - run: opam install --deps-only .
 
-      - name: Build components
-        run: opam exec -- make all
+      - run: opam exec -- make all