Update QuantConnect.pythonnet to 2.0.64

[jhonabreul]

Description

Updates the QuantConnect.pythonnet package reference to 2.0.64 in the 11 csproj that consume it.

Related Issue

N/A — routine dependency update. Brings in QuantConnect/pythonnet#141.

Motivation and Context

pythonnet 2.0.64 fixes two property-assignment bugs surfaced by a user algorithm report:

• Failed Python-to-CLR conversions at silent Converter.ToManagedValue exits now raise a proper TypeError: '<type>' value cannot be converted to <T> instead of leaving the error indicator unset, which manifested in Lean as the opaque SystemError: error return without exception set during algorithm initialization.
• C# properties with private setters are now read-only from Python (TypeError: property is read-only); previously a Python assignment like self.universe_manager = ... silently overwrote QCAlgorithm.UniverseManager { get; private set; } through reflection, corrupting engine state.

NOTE: opened as draft — QuantConnect/pythonnet#141 is not merged yet, so 2.0.64 is not on NuGet; will mark ready once the package is indexed.

Requires Documentation Change

No.

How Has This Been Tested?

• pythonnet 2.0.64: full embed test suite green on Python 3.8–3.14 (PR Open source user Interface #141 CI) and the pytest suite green.
• End-to-end against Lean master with the 2.0.64 Python.Runtime.dll: a Python algorithm assigning a non-convertible object to self.universe_manager now fails with a clear TypeError: property is read-only at the offending line instead of error return without exception set.

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. (Version bump only; the behavioral changes are covered by tests in Raise a proper TypeError when a property assignment cannot be performed pythonnet#141.)
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>