Stop suppressing ssh-keyscan stderr in Set up SSH key step

The step failed silently (exit 1, no message) because stderr was
redirected to /dev/null while sh -e aborts on ssh-keyscan's non-zero
exit. Let the real error (DNS/firewall/etc.) show up in the log.

.gitea/workflows/build-deploy.yml

@@ -31,8 +31,8 @@ jobs:
           mkdir -p ~/.ssh
           printf '%s\n' "$DEPLOY_SSH_KEY" > ~/.ssh/deploy_key
           chmod 600 ~/.ssh/deploy_key
-          ssh-keyscan -H git.haemka.in >> ~/.ssh/known_hosts 2>/dev/null
-          ssh-keyscan -H -p "${DEPLOY_PORT:-22}" "$DEPLOY_HOST" >> ~/.ssh/known_hosts 2>/dev/null
+          ssh-keyscan -H git.haemka.in >> ~/.ssh/known_hosts
+          ssh-keyscan -H -p "${DEPLOY_PORT:-22}" "$DEPLOY_HOST" >> ~/.ssh/known_hosts
 
       - name: Fetch theme submodule
         run: |