[release only] Bump minor to release 2.1.2

[atalman]

Same as https://github.com/pytorch/audio/pull/3653

[pytorch-bot[bot]]

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:test_tube: See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/audio/3705

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As of commit 087d98927dc4e1f9f9c1dc0f40471cccda15d0ac with merge base 5ee254e350289ee2951cc61a1fdc3b361c48a265 (): :green_heart: Looks good so far! There are no failures yet. :green_heart:

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