fix: use full path and check before shredding

.gitea/workflows/deploy.yaml

@@ -10,7 +10,7 @@ jobs:
 
       - name: Build article code
         run: |
-          nix-build -A articles
+          /run/current-system/sw/bin/nix-build -A articles
 
       - name: Deploy article HTML
         run: |
@@ -18,10 +18,10 @@ jobs:
           ${{ secrets.DEPLOY_SSH_KEY }}
           EOD
 
-          nix-shell -p rsync openssh --run \
+          /run/current-system/sw/bin/nix-shell -p rsync openssh --run \
             'rsync -avz -e "ssh -oStrictHostKeyChecking=accept-new -i ssh-key" result/* deploy@andrew.riouxs.co:/srv/site'
 
       - name: Remove SSH key
         if: always()
         run: |
-          shred ssh-key
+          test -f ssh-key && shred ssh-key