Migrate important library projects to Java 11

[jurgenvinju]

These are projects which will need to be upgraded still to java 11, which are not on usethesource (yet):

• [x] flybytes
• [x] clair
• [ ] php-air
• [ ] python-air
• [ ] js-air

Originally posted by @jurgenvinju in https://github.com/usethesource/usethesource.github.io/issues/16#issuecomment-1002962533