Builds with GitHub actions

[drupol]

Hello,

I discovered this book a couple of weeks ago and I learned a lot from it so I wanted to bring my stone to the building.

The idea that I had in mind was an easy way for everyone to see the result of each new change, without the hassle of building PDFs, without the hassle of using docker and/or having LaTeX installed locally.

This PR:

• [x] Provide a Github Action workflow that builds all the PDF versions;
• [x] Create a github pre-release for each commit and upload the generated PDF assets;
• [x] Add missing required fonts in src/fonts;
• [x] Provide the generated PDF as build artifacts

You can find the outcome of this on my fork: https://github.com/drupol/milewski-ctfp-pdf/actions/runs/175561730 And the automatic pre-release that was created with all the assets uploaded: https://github.com/drupol/milewski-ctfp-pdf/releases/tag/8bb1afd

Edit: I made a first version, the building time was 50 min, then an updated version where I'm down to 14 min by running concurrent builds. I'm pretty sure there are ways to improve this.

[hmemcpy]

This is amazing, thanks so much for doing this! I'll have a look tonight and will merge it ASAP!

[drupol]

This is amazing, thanks so much for doing this! I'll have a look tonight and will merge it ASAP!

Thanks :-)

[hmemcpy]

Thank you again for the effort! I'll have it set up and hopefully working soon!