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
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 4bae28b..077599a 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -100,8 +100,8 @@
     maven_jar(
         name = "jgit",
         artifact =
-            "org.eclipse.jgit:org.eclipse.jgit:5.5.1.201910021850-r",
-        sha1 = "e0ba7a468e8c62da8521ca3a06a061d4dde95223",
+            "org.eclipse.jgit:org.eclipse.jgit:5.8.0.202006091008-r",
+        sha1 = "1d8b1a904ae018e9973f6bd92f71065c629393e3",
     )
 
     maven_jar(