Update pgproto to latest from typings branch

bryanforbes · bryanforbes · commit c21ccd73eb00 · 2020-05-18T15:04:18.000-05:00
diff --git a/asyncpg/pgproto b/asyncpg/pgproto
@@ -1 +1 @@
-Subproject commit c6cdeac87c33783165372baefa86f596fa78026f
+Subproject commit df836e68ec415d134d837e4d16d72c3d42bae881
