bugfix: libs: Update 'breathe' submodule pointer (#846)

davidvandebunte · deanberris · commit b9a864e160a6 · 2018-06-05T10:44:39.000+10:00
This project recently had its history rewritten, and the SHA we referred to no longer exists. See discussion here: #582
diff --git a/libs/network/doc/_ext/breathe b/libs/network/doc/_ext/breathe
@@ -1 +1 @@
-Subproject commit 853385ef4f0c3dd126887750e20d5f7456065998
+Subproject commit a564b991b5eb2dc220ca29ef21b9c68bdc2f8ac6
