[Sonar][MAJOR/VULNERABILITY] Avoid using this unsafe code block.

[github-actions]

Sonar issue: AZ-m77OToUUmmpKU650Q
Project: GameFrameX.Foundation
Branch: main
Severity: MAJOR
Type: VULNERABILITY
Rule: csharpsquid:S6640
Location: GameFrameX.Foundation:GameFrameX.Foundation.Json/UnicodeJsonEncoder.cs:121

Message:
Avoid using this unsafe code block.

[linear-code]

GFX-255