fix(deps): update dependency alembic to ~1.15.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
alembic (source, changelog)	~1.7.6 -> ~1.15.0

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: poetry.lock

Updating dependencies
Resolving dependencies...

The "poetry.dev-dependencies" section is deprecated and will be removed in a future version. Use "poetry.group.dev.dependencies" instead.
Creating virtualenv todo-bot-p8ErBURW-py3.10 in /home/ubuntu/.cache/pypoetry/virtualenvs

The current project's supported Python range (>=3.8,<3.11) is not compatible with some of the required packages Python requirement:
  - alembic requires Python >=3.9, so it will not be installable for Python >=3.8,<3.9

Because no versions of alembic match >=1.15.0,<1.15.1 || >1.15.1,<1.16.0
 and alembic (1.15.1) requires Python >=3.9, alembic is forbidden.
So, because todo-bot depends on alembic (~1.15.0), version solving failed.

  * Check your dependencies Python requirement: The Python requirement can be specified via the `python` or `markers` properties

    For alembic, a possible solution would be to set the `python` property to ">=3.9,<3.11"

    https://python-poetry.org/docs/dependency-specification/#python-restricted-dependencies,
    https://python-poetry.org/docs/dependency-specification/#using-environment-markers