SASTBot: Monthly dependency updates for 16.10

What does this MR do?

• upgrade github.com/stretchr/testify version [v1.8.4 => v1.9.0]
• upgrade gitlab.com/gitlab-org/security-products/analyzers/ruleset/v2 version [v2.0.7 => v2.0.8]
• upgrade go version to 1.21 and 1.21.5 for non-FIPS and FIPS images, respectively

What are the relevant issue numbers?

• https://gitlab.com/gitlab-org/security-products/release/-/issues/148+

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer