CompatHelper: bump compat for "VectorizationBase" to "0.20"

[github-actions]

This pull request changes the compat entry for the VectorizationBase package from 0.19 to 0.19, 0.20.

This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[chriselrod]

The changes in VectorizationBase 0.20 shouldn't matter for anything but LoopVectorization, so this should be fine.

[JeffreySarnoff]

I see no downside. Merging tomorrow absent other comments.

[JeffreySarnoff]

got this error message

The page build failed for the `master` branch with the following error:
Unable to build page. Please try again later.

For information on troubleshooting Jekyll see:
  https://docs.github.com/articles/troubleshooting-jekyll-builds

raised the patch level and am retrying

[JeffreySarnoff]

All is as it should be (thank you Dilum Aluthge).