Delete leftover JLD2 files before deploying docs

[ali-ramadhan]

Maybe not the cleanest solution but this will resolve #509 which has become a rather annoying issue recently.

[ali-ramadhan]

This PR should be merged first before to avoid any more JLD2 files being committed to git history.

[codecov]

Codecov Report

Merging #558 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #558   +/-   ##
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  Coverage   67.72%   67.72%           
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  Files          69       69           
  Lines        1952     1952           
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  Hits         1322     1322           
  Misses        630      630

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[glwagner]

Reluctant approval.

This is not a good solution, because its useful for users to have the JLD2 file around to play with.

We need to know why such behavior occurs so we can ensure it doesn't happen in the future --- how is the file being added from gh-pages, when jld2 is ignored in gitignore?

[ali-ramadhan]

Actually I think I did it wrong in #524. I'm supposed to delete leftover files after makedocs but before deploydocs. So I'll modify this PR to do that.

I also feel that Documenter shouldn't even be adding jld2 files. Asking on Julia Slack to see if this is expected behavior and how to avoid it.

EDIT: There is no .gitignore file on gh-pages so we just have to add one there with *.jld2.

[ali-ramadhan]

I added a .gitignore to the gh-pages branch so we should be good now.

This PR now deletes leftover JLD2 files before deploying (just to be safe and also to unclutter the CI server in case we need to cache files between builds).