ci: Use checkout v5

Author: jcs090218

.github/workflows/build-proxy.yml

@@ -36,7 +36,7 @@ jobs:
         - win-x64
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
 
     - name: Install dependencies
       run: |

.github/workflows/test-elisp.yml

@@ -36,7 +36,7 @@ jobs:
           experimental: true
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
 
     - uses: jcs090218/setup-emacs@master
       with: