for reqExecutions execFilter cannot be empty

[charlesverge]

Description

reqExecutionsAsync will time out if the execFilter is left blank due to the api not responding to the request. At minimum it needs the client id. This change sets a default to the execFilter to prevent the client from hanging. It may not solve all issues mentioned in #82

Testing

Execute connectAsync with raiseSyncError = True and execute reqExecutionsAsync with no filter.

from ib_async import IB
import asyncio


async def main():
    app = IB()

    await app.connectAsync("127.0.0.1", 4001, clientId=5, raiseSyncErrors=True)
    executions = await app.reqExecutionsAsync()
    print("Executions:", executions)
    app.disconnect()


asyncio.run(main())