chore(ci): define commit sha for actions/checkout (#413)

Updates the publish.yml file setting the commit sha to pin the
actions/checkout Github action version.

Signed-off-by: José Guilherme Vanz <jguilhermevanz@suse.com>

Author: jvanz

.github/workflows/publish.yml

@@ -24,7 +24,7 @@ jobs:
           sudo apt install hugo
           hugo version
       - name: Checkout Repo
-        uses: actions/checkout@master
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: true
       - name: Setup Pages