chore: fix critical vulnerabilities with dependencies

[ohorbachevskyi]

What/Why/How?

• upgrade gulp-mocha to ^9.0.0 - fixes https://github.com/Redocly/openapi-sampler/security/dependabot/17 . The latest version of [email protected] breaks run scripts from package.json, so it requires code changes.
• replace coverall package with its fork coveralls-next - fixes https://github.com/Redocly/openapi-sampler/security/dependabot/47 and https://github.com/Redocly/openapi-sampler/security/dependabot/42. There is an old opened issue with replacing deprecated request package, which was fixed in the fork. Maybe we can create own fork?

Reference

https://github.com/Redocly/openapi-sampler/security/dependabot/17
https://github.com/Redocly/openapi-sampler/security/dependabot/42
https://github.com/Redocly/openapi-sampler/security/dependabot/47

Testing

Screenshots (optional)

Check yourself

• Code is linted
• Tested
• All new/updated code is covered with tests

Security

• Security impact of change has been considered
• Code follows company security practices and guidelines

[AlexVarchuk]

make sure all works fine with new updated version. Thanks

[ohorbachevskyi]

make sure all works fine with new updated version. Thanks

@AlexVarchuk Yes, it's dev dependencies upgrade, so I checked package scripts with gulp, they work as previously.