message: Update badge to new workflow location
diff: <p align="center">
  <a href="https://github.com/duckdb/duckdb/actions">
  - <img src="https://github.com/cwida/duckdb/workflows/.github/workflows/main.yml/badge.svg?branch=master" alt=".github/workflows/main.yml">
  + <img src="https://github.com/duckdb/duckdb/actions/workflows/Main.yml/badge.svg?branch=master" alt="Github Actions Badge">
  </a>
  <a href="https://www.codefactor.io/repository/github/cwida/duckdb">
  <img src="https://www.codefactor.io/repository/github/cwida/duckdb/badge" alt="CodeFactor"/>
  