Removed runtime.txt and fixed poetry.lock

[rhysyngsun]

What are the relevant tickets?

N/A

Description (What does it do?)

This fixes the heroku deployments that broke due to the switch to Poetry:

• Removes runtime.txt since Heroku is erroring on it being present since Heroku just reads the runtime from pyproject.toml.
• Ran poetry lock --no-update since Heroku is generating a warning for this
• Added poetry lock --check to the CI actions so that we catch lockfile issues before they get merged.
• Fixed indentation issue in ci.yaml.

How can this be tested?

• Tests should pass