Bump CI versions

Author: rossberg

.github/workflows/ci-spec.yml

@@ -75,7 +75,7 @@ jobs:
     needs: [build-core-spec]
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           submodules: "recursive"
       - name: Setup TexLive
@@ -94,7 +94,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           submodules: "recursive"
       - name: Setup TexLive