fix packaging and md syntax issues

[wiseaidev]

High Level Overview of Change

• Made the package pep-561 compatible by Including the root py.typed file in the package.
• Removed redundant py.typed files.
• Updated poetry and poetry-core.
• Fixed markdown syntax.
• Fixed a flake8 issue.
• Removed an unnecessary MANIFEST.in file.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Tests (You added tests for code that already exists, or your new feature included in this PR)
• Documentation Updates
• Release

Test Plan

I haven't tested these changes yet. I will be working on it later, or you can trigger the CI.

Context

Note that the new version of poetry introduced new arguments like --group. For example, you can run the following commands to:

• Install the main dependencies only:

poetry install --only main

• Install the dev dependencies:

poetry install --only dev

• Add a new dependency to dev:

poetry add pytest --group dev

• Add a new dependency to main:

poetry add requests

You can refer to python-poetry.org/docs/cli for more info.

[mvadari]

Will removing all the individual py.typed in individual folders support the syntax of from xrpl.models import ...?

[JST5000]

@wiseaidev Do you happen to know an answer to mvadari's question about whether this will still allow for individual files to be imported with types?

[mvadari]

Please avoid running poetry update in this PR so that we don't have issues with dependencies.