Added PlantUML version 1.2020.17

[RohanTalip]

• Added this version to the plantumlVersions list in utils.js
• Added plantuml.1.2020.17.jar (named with a period after "plantuml" rather than a hyphen, as this is what it is named on https://sourceforge.net/projects/plantuml/files/1.2020.17/ )

[RohanTalip]

FYI, node-plantuml, which you use, has a script to download versions of PlantUML: https://github.com/markushedvall/node-plantuml/blob/e4ee91aab31d3dc19056ec993926df3b153a4839/scripts/get-plantuml-jar.js

Maybe use that instead of including binary .jar files in your git repository? You could save and compare hashes like SHA-512/224,
SHA-512/256 or one of the SHA3 hashes if you're concerned about files being tampered.

[adrianvlupu]

Thanks for the suggestion. I think I tried using the script at some point but can't remember what failed.
I expect to remove the jar files at some point, but for now people still have trouble with versioning over at https://github.com/plantuml-stdlib/C4-PlantUML.

Sorry for not maintaining this, I still use it frequently though.