Upgrade JGit to 5.8.0.202006091008-r

Aligns with the base version used starting from core Gerrit 3.1.5. This
is the jgit released version that first had commit a79c5b1f1, to which
core points to since gerrit v3.1.5.

Change-Id: Ie500c4204aea30bd8186c4d8ca18d7e2d4642be4
1 file changed