fix download method issue when gid is 0

Author: theoephraim

src/lib/GoogleSpreadsheet.ts

@@ -460,7 +460,8 @@ export class GoogleSpreadsheet {
  params: {
  id: this.spreadsheetId,
  format: fileType,
- ...worksheetId && { gid: worksheetId },
+ // worksheetId can be 0
+ ...worksheetId !== undefined && { gid: worksheetId },
  },
  responseType: returnStreamInsteadOfBuffer ? 'stream' : 'arraybuffer',
  });