fix: add SSH options to sftp to allow sshpass password auth

sftp -b - (batch mode) suppresses the interactive password prompt that
sshpass relies on to inject the password. SSH then tried pubkey (failed)
and a non-interactive password attempt (failed), giving:

  Permission denied (publickey,password). Connection closed.

Fix: pass -o PubkeyAuthentication=no -o PreferredAuthentications=password
to sftp so SSH skips pubkey entirely and goes straight to the password
exchange, which sshpass -e can then satisfy from the SSHPASS env var.

Co-authored-by: igaw <1050803+igaw@users.noreply.github.com>

Author: Copilot

.github/workflows/upload.yml

@@ -82,7 +82,10 @@ jobs:
               [ -f "$f" ] || continue
               echo "put $f $(basename "$f")"
             done
-          ) | sshpass -e sftp -b - "${SFTP_USERNAME}@${SFTP_SERVER}"
+          ) | sshpass -e sftp -b - \
+                -o PubkeyAuthentication=no \
+                -o PreferredAuthentications=password \
+                "${SFTP_USERNAME}@${SFTP_SERVER}"
 
   upload-release-assets:
     name: upload GitHub release assets