Prepare release 1.31.1/0.52b1 (#4496)

[release/v1.31.x-0.52bx] Prepare release 1.31.0/0.52b0 (#4481)

* Prepare release 1.31.0/0.52b0

* Update contrib sha

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Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>

Update contrib sha

[release/v1.30.x-0.51bx] Prepare release 1.30.0/0.51b0 (#4408)

[release/v1.29.x-0.50bx] Prepare release 1.29.0/0.50b0 (#4349)

* Prepare release 1.29.0/0.50b0

* Update CONTRIB_REPO_SHA to opentelemetrybot/prepare-release-1.29.0-0.50b0

* Update CONTRIB_REPO_SHA for misc too

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Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>

[release/v1.28.x-0.49bx] Prepare release 1.28.2/0.49b2 (#4290)

* Prepare release 1.28.2/0.49b2

* Update CONTRIB_REPO_SHA to point to contrib release branch

* Update date to today Nov 18

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Co-authored-by: Aaron Abbott <aaronabbott@google.com>

[release/v1.28.x-0.49bx] Prepare release 1.28.1/0.49b1 (#4262)

Update .readthedocs.yml

Skip testpypi

Skip test pypi