#296 chore: update submodule dependencies to latest main

Updates submodule dependencies

This PR updates the go.mod files in submodules to reference the latest commit from main.

Updated to: v1.26.3-0.20261102103018-bb4439a5fcc1
Updated modules: customrules converter-tests cmd

Changes:

• Updated github.com/speakeasy-api/openapi dependency in submodule go.mod files
• Ran go mod tidy to update dependencies

---

This PR was automatically created by the update-submodule-dependencies workflow

---

Summary by cubic

Updates submodule go.mod files to reference the latest commit on main of github.com/speakeasy-api/openapi.

• Bumps the dependency to v1.26.3-0.20261102103018-bb4439a5fcc1 in cmd, customrules, and converter-tests.
• Runs go mod tidy to keep the module graph consistent.