workflows/deploy: Fetch all commits on checkout

This should fix the issue where all pages have the same last-modified
date.

Signed-off-by: Evan Maddock <maddock.evan@vivaldi.net>

Author: EbonJaeger

.github/workflows/deploy.yml

@@ -10,7 +10,9 @@ jobs:
     name: Deploy to GitHub Pages
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
       - uses: actions/setup-node@v4
         with:
           node-version: 22