Update .github/workflows/pr-validate.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: simongdavies

.github/workflows/pr-validate.yml

@@ -24,6 +24,8 @@ jobs:
       docs-only: ${{ steps.docs-only.outputs.result }}
     steps:
       - uses: actions/checkout@v6
+        with:
+          fetch-depth: 2
       - uses: dorny/paths-filter@v3
         id: changes
         with: