Update QuantConnect.pythonnet to 2.0.56

[jhonabreul]

Description

Bumps the QuantConnect.pythonnet package reference from 2.0.54 to 2.0.56 across all projects that consume it (11 .csproj files).

Ref: QuantConnect/pythonnet#126

Related Issue

N/A — routine dependency version bump.

Motivation and Context

Keeps the LEAN solution on the latest QuantConnect Python.NET runtime build, picking up the reimplemented AttributeError member-name suggestions (now via tp_getattro, replacing the 2.0.55 __getattr__ hook that was reverted).

Requires Documentation Change

No.

How Has This Been Tested?

Version bump only — no source code changed. The updated package restores and builds via the standard solution build; existing CI (build + unit/regression suites) validates the runtime.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>