Bump spectral-core version

[kornel-kotan-sonarsource]

Motivation and Context

This change is required to fix compilation errors that occur when HTTP response codes are defined as numbers instead of strings in OpenAPI specifications. The issue was present in spectral-core version 1.18.x and has been resolved in version 1.20.0.

Related issue: stoplightio/spectral#955

Description

Updated @stoplight/spectral-core dependency from version ^1.18.3 to ^1.20.0 in package.json. This version includes fixes for handling HTTP response codes defined as numbers in OpenAPI specifications, which previously caused compilation errors.

The update ensures compatibility with OpenAPI specifications that use numeric response codes (e.g., 200, 404) instead of string representations (e.g., "200", "404").

How Has This Been Tested?

• Dependencies were updated using npm install
• TypeScript compilation was verified by running npm run build - no compilation errors
• The project builds successfully with the updated spectral-core version
• No unit tests were added as this is a dependency update that fixes existing functionality

Code reviewers can verify the changes by:

1. Checking that the spectral-core version in package.json is updated to ^1.20.0
2. Running npm run build to ensure TypeScript compilation succeeds
3. Testing with OpenAPI specs that have numeric response codes

Screenshot(s)/recordings(s)

Not applicable - this is a dependency update.

Types of changes

• 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 change)

Checklist

• This PR's code follows as closely as possible the coding style/guidelines of this project.
• I have added error reporting and followed the error reporting guidelines.
• I have added event tracking and followed the event tracking guidelines.
• I have updated any relevant documentation accordingly to reflect this PR's changes.
• I have added automated tests (unit/integration/e2e/other) to cover my changes.
• All new and existing tests pass locally (excluding flaky CI tests).

[emma-patterson-sonarsource]

Thanks for this! Hope we can get this sorted asap!

[mnaumanali94]

This should be fixed here https://github.com/stoplightio/spectral-action/releases/tag/v0.8.13 @kornel-kotan-sonarsource