chore(main): release 2.8.1-SNAPSHOT (#850)

:robot: I have created a release *beep* *boop*
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### Updating meta-information for bleeding-edge SNAPSHOT release.

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This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).
6 files changed
tree: e1ee7aa0f4f417baff221d269944de0f3193df59
  1. java-core/