GObject.ParamSpec.* blurb and nick are nullable

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Description

GObject.ParamSpec.* blurb and nick are nullable now

Related Issue

Fixes #218

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Type definition update
• Documentation update

Validation

Test Location: examples/gobject-param-spec/main.ts

Test Case:

// Minimal test case demonstrating the changes
import GObject from 'gi://GObject';

GObject.ParamSpec.string(
        "title",
        null,
        null,
        GObject.ParamFlags.READWRITE,
        "",
      )

Expected Behavior:

1. Code should compile without type errors
2. Runtime behavior should match documentation/GJS implementation

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes
• I have updated the documentation accordingly