fix: update Go version to 1.23 and configure Renovate to prevent pre-release versions

[lgallard]

Summary

• Fixed Go version from invalid 1.25 to stable 1.23 in test.yml and security.yml workflows
• Added Renovate configuration to prevent future pre-release Go version suggestions

Changes

• Updated .github/workflows/test.yml to use Go version 1.23 (was using non-existent 1.25)
• Updated .github/workflows/security.yml to use Go version 1.23 (was using non-existent 1.25)
• Enhanced renovate.json with rules to:
  • Ignore unstable golang-version datasource releases
  • Prevent unstable versions for actions/setup-go action
  • Add ignoreUnstable to existing Go datasource rule

Test Plan

• GitHub Actions tests should now pass with valid Go version
• Security scans should complete successfully
• Renovate will no longer suggest pre-release Go versions