message: updated CDN for v2.4.0
diff: <!-- RELEASE (CDN)
  -->
  - <script src="https://cdn.jsdelivr.net/gh/gitbrent/pptxgenjs/dist/pptxgen.bundle.js"></script>
  - <script src="https://cdn.jsdelivr.net/gh/gitbrent/pptxgenjs/examples/pptxgenjs-demo.js"></script>
  + <script src="https://cdn.jsdelivr.net/gh/gitbrent/pptxgenjs@2.4.0/dist/pptxgen.bundle.js"></script>
  + <script src="https://cdn.jsdelivr.net/gh/gitbrent/pptxgenjs@2.4.0/examples/pptxgenjs-demo.js"></script>
  <!-- OFFICE365 TESTING:
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