chore: update protobuf v3.15.3

Google APIs · copybara-github · commit f6dd7e476205 · 2021-02-26T10:00:24.000-08:00
This release makes --experimental_allow_proto3_optional no longer necessary.

PiperOrigin-RevId: 359781040
diff --git a/WORKSPACE b/WORKSPACE
@@ -47,9 +47,9 @@ http_archive(
 
 http_archive(
     name = "com_google_protobuf",
-    sha256 = "d0f5f605d0d656007ce6c8b5a82df3037e1d8fe8b121ed42e536f569dec16113",
-    strip_prefix = "protobuf-3.14.0",
-    urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.14.0.tar.gz"],
+    sha256 = "b10bf4e2d1a7586f54e64a5d9e7837e5188fc75ae69e36f215eb01def4f9721b",
+    strip_prefix = "protobuf-3.15.3",
+    urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.15.3.tar.gz"],
 )
 
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
