updated checkout branch to source

Author: Adir111

.github/workflows/update-hkubectl-downloads.yaml

@@ -14,7 +14,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: kube-HPC/kube-HPC.github.io
-          ref: main
+          ref: source
 
       - name: Download latest release files from hkubectl
         run: |