fix: Upgrade duckduckgo-search to version 5.1.0 & update document segment api parameter error

[shjyh]

fix: Upgrade duckduckgo-search to version 5.1.0 to fix RateLimit error
fix: dataset api (update document segment) parameter handling error

Description

1. Update duckduckgo-search dependency version to fix RateLimite error in some scenarios
2. Fix the update document segment interface error, correct the parameter transmission error, and rename the parameter name

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (Only absorb the update document segment api interface /)
• Dependency upgrade

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods
• optional I have made corresponding changes to the documentation
• optional I have added tests that prove my fix is effective or that my feature works
• optional New and existing unit tests pass locally with my changes