Update XLSX dependency

[pintaf]

Hello.

I just noticed that the XLSX lib (on which you depend) hasn't been updated on npmjs.com since 4 years. I first though it was simply not maintained anymore until I found out that it continued to evolve but was simply not published to npmjs.com anymore.

Why? I don't know.

On the top of the readme of the npm linked github, there is this announcement:

While the npmJS version is 0.18.5, the version on their new repo is 0.20.3 Here is the way to install the updated lib: https://docs.sheetjs.com/docs/getting-started/installation/frameworks/ It is recommended to "vendor" it: https://docs.sheetjs.com/docs/getting-started/installation/frameworks/#vendoring

You might want to update it as it might iron out some issues and also update this lib's codebase that otherwise hasn't moved since 4 years.