Merge tag 'v1.10.0rc3' into develop

Synapse 1.10.0rc3 (2020-02-10)
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Features
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- Filter out m.room.aliases from the CS API to mitigate abuse while a better solution is specced. ([\#6878](https://github.com/matrix-org/synapse/issues/6878))

Internal Changes
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- Fix continuous integration failures with old versions of `pip`, which were introduced by a release of the `zipp` library. ([\#6880](https://github.com/matrix-org/synapse/issues/6880))