Add 'once' support

Hello, guys).

Just discovered that Stream extends EventEmitter, and EventEmitter has once() method, which really helpful in some cases.

Can you add, please, once(event: "report", listener: (report: Report) => void): this; to IStream?)

Current workaround is:

return new Promise<IPullPriceFeedResponse>(async (resolve, reject) => {
      (this.stream as unknown as EventEmitter).once('report', (report) => {
        try {
          const decoded = decodeReport(report.fullReport, report.feedID) as DecodedV3Report;

          resolve(decoded);
        } catch (error) {
          reject(error);
        }
      })
    })

Best regards.

Locate the IStream declaration and the Stream implementation described as extending EventEmitter, then inspect how existing event methods are typed. Add the requested once signature for report listeners and verify that the public stream interface exposes it consistently with the EventEmitter behavior.