Upgrade guava to 28.0-jre

Change-Id: I5cb8c5b1d077353da35b2ef4d8bfc1fe566b12c5
diff --git a/lib/guava.bzl b/lib/guava.bzl
index c36bf14..9f0ff32 100644
--- a/lib/guava.bzl
+++ b/lib/guava.bzl
@@ -1,5 +1,5 @@
-GUAVA_VERSION = "27.1-jre"
+GUAVA_VERSION = "28.0-jre"
 
-GUAVA_BIN_SHA1 = "e47b59c893079b87743cdcfb6f17ca95c08c592c"
+GUAVA_BIN_SHA1 = "54fed371b4b8a8cce1e94a9abd9620982d3aa54b"
 
 GUAVA_DOC_URL = "https://google.github.io/guava/releases/" + GUAVA_VERSION + "/api/docs/"