ci: use actions/checkout@v5

Author: inkydragon

.github/workflows/CI.yml

@@ -17,7 +17,7 @@ jobs:
           - '1'
           - 'nightly'
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
@@ -40,7 +40,7 @@ jobs:
       contents: write
       statuses: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'