Prepare for (pre) release: v5.6.0rc1

[Nusnus]

CI passes locally on Mac:

  3.13-unit: OK (221.86=setup[110.92]+cmd[110.94] seconds)
  3.13-linux-integration-py-amqp: OK (215.55=setup[168.75]+cmd[46.81] seconds)
  3.13-linux-integration-redis: OK (159.48=setup[139.54]+cmd[19.94] seconds)
  3.13-linux-integration-mongodb: OK (443.21=setup[217.08]+cmd[226.14] seconds)
  3.13-linux-integration-kafka: OK (219.04=setup[157.99]+cmd[61.06] seconds)
  congratulations :) (443.82 seconds)
  clean: OK (20.41=setup[17.92]+cmd[1.23,1.26] seconds)
  lint: OK (90.73=setup[17.56]+cmd[73.17] seconds)
  mypy: OK (86.94=setup[45.75]+cmd[41.19] seconds)
  parallel: OK (467.09=setup[21.78]+cmd[445.31] seconds)
  congratulations :) (467.78 seconds)

[cclauss]

Python 3.8 has been end-of-life for a year now, and it is blocking several dependency upgrade pull requests.

Will Py3.8 be removed in this release?

[auvipy]

after this release