Upgrade mockito-core to 2.28.2

Change-Id: I2be328c62e3b20d3ebbe230637808e87dea3fcf5
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 1f65ede..995dbe3 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -9,8 +9,8 @@
 
     maven_jar(
         name = "mockito",
-        artifact = "org.mockito:mockito-core:2.27.0",
-        sha1 = "835fc3283b481f4758b8ef464cd560c649c08b00",
+        artifact = "org.mockito:mockito-core:2.28.2",
+        sha1 = "91110215a8cb9b77a46e045ee758f77d79167cc0",
         deps = [
             "@byte-buddy//jar",
             "@byte-buddy-agent//jar",