Update default FPGA part number from KU115 to VU13P

Description

• Update default FPGA part number from KU115 to VU13P, as more commonly used by hls4ml users (e.g., for CMS Phase-2 Level-1 Trigger)

Type of change

• Documentation update
• Other: Default configuration change

Tests

• Checking in CI

Checklist

• I have read the guidelines for contributing.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have installed and run pre-commit on the files I edited or added.
• I have added tests that prove my fix is effective or that my feature works.