Upgrade guice to 4.2.1

To match the version used in core Gerrit 2.16.

Change-Id: I3f54e8ec7aca2289d22eafeb652cc2633aaa3c49
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 51389e6..d86da25 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -82,18 +82,18 @@
         sha1 = "6a806eff209f36f635f943e16d97491f00f6bfab",
     )
 
-    GUICE_VERS = "4.2.0"
+    GUICE_VERS = "4.2.1"
 
     maven_jar(
         name = "guice",
         artifact = "com.google.inject:guice:" + GUICE_VERS,
-        sha1 = "25e1f4c1d528a1cffabcca0d432f634f3132f6c8",
+        sha1 = "f77dfd89318fe3ff293bafceaa75fbf66e4e4b10",
     )
 
     maven_jar(
         name = "guice-assistedinject",
         artifact = "com.google.inject.extensions:guice-assistedinject:" + GUICE_VERS,
-        sha1 = "e7270305960ad7db56f7e30cb9df6be9ff1cfb45",
+        sha1 = "d327e4aee7c96f08cd657c17da231a1f4a8999ac",
     )
 
     maven_jar(