Update mockito to 2.23.4

Also update its dependency byte buddy to 1.9.3.

Change-Id: I23d224db808e8620ac136c428f75a467065e0528

external_plugin_deps.bzl

diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 6bb1ec6..d117e7b 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -3,8 +3,8 @@
 def external_plugin_deps():
     maven_jar(
         name = "mockito",
-        artifact = "org.mockito:mockito-core:2.23.0",
-        sha1 = "497ddb32fd5d01f9dbe99a2ec790aeb931dff1b1",
+        artifact = "org.mockito:mockito-core:2.23.4",
+        sha1 = "a35b6f8ffcfa786771eac7d7d903429e790fdf3f",
         deps = [
             "@byte-buddy//jar",
             "@byte-buddy-agent//jar",
@@ -12,18 +12,18 @@
         ],
     )
 
-    BYTE_BUDDY_VERSION = "1.9.0"
+    BYTE_BUDDY_VERSION = "1.9.3"
 
     maven_jar(
         name = "byte-buddy",
         artifact = "net.bytebuddy:byte-buddy:" + BYTE_BUDDY_VERSION,
-        sha1 = "8cb0d5baae526c9df46ae17693bbba302640538b",
+        sha1 = "f32e510b239620852fc9a2387fac41fd053d6a4d",
     )
 
     maven_jar(
         name = "byte-buddy-agent",
         artifact = "net.bytebuddy:byte-buddy-agent:" + BYTE_BUDDY_VERSION,
-        sha1 = "37b5703b4a6290be3fffc63ae9c6bcaaee0ff856",
+        sha1 = "f5b78c16cf4060664d80b6ca32d80dca4bd3d264",
     )
 
     maven_jar(