mongodb 如何查询 6 月有记录， 7、8 月没有记录的结果集

[BBB]

数据库数据：

{"_id":"1", "uid":"001", "records":1, "month":"2021-06"},
{"_id":"2", "uid":"001", "records":2, "month":"2021-07"},
{"_id":"3", "uid":"001", "records":3, "month":"2021-08"},
{"_id":"4", "uid":"002", "records":2, "month":"2021-06"},
{"_id":"5", "uid":"002", "records":2, "month":"2021-07"},
{"_id":"6", "uid":"003", "records":2, "month":"2021-06"},
{"_id":"7", "uid":"003", "records":2, "month":"2021-08"},
{"_id":"1", "uid":"004", "records":1, "month":"2021-07"},
{"_id":"1", "uid":"004", "records":2, "month":"2021-08"},
{"_id":"1", "uid":"005", "records":1, "month":"2021-06"},
{"_id":"1", "uid":"006", "records":2, "month":"2021-06"},

期望查询结果：
{"uid":"005"},
{"uid":"006"}

[jxxz]

聚合 最大的 month 为 2021-06