Update cryptography and certifi to resolve dependabot security alerts.

[mpeddada1]

• https://github.com/googleapis/gapic-generator-java/security/dependabot/6
• https://github.com/googleapis/gapic-generator-java/security/dependabot/14
• https://github.com/googleapis/gapic-generator-java/security/dependabot/12