New Features

• feat(dc): Add executeQuery and executeMutation APIs to Data Connect (#2979)

Miscellaneous

• [chore] Release 13.6.0 (#3006)
• build(deps-dev): bump gulp from 5.0.0 to 5.0.1 (#3001)
• build(deps): bump @firebase/database-compat from 2.0.6 to 2.1.0 (#3002)
• build(deps): bump @fastify/busboy from 3.1.1 to 3.2.0 (#2998)
• build(deps-dev): bump @firebase/api-documenter from 0.4.0 to 0.5.0 (#3000)
• build(deps): bump axios in /.github/actions/send-email (#2983)
• chore(dc): Implement gen tracking (#2985)
• FDC: update api version, integration tests, and CONTRIBUTING.md (#2972)
• chore: update copyright headers from Google Inc. to Google LLC (#2974)