Update git submodules

* Update docs/submodules/snaps from branch 'stable/fraser'
  - Remove conditional on external_fixed_ips to allow for case that
    it is not set but network_id is set in external_gateway_info

    Change-Id: Ib0fdfbf49730ca68d7c1d47c18c2ac17be637380
    Signed-off-by: Stuart Mackie <wsmackie@juniper.net>
    (cherry picked from commit 26645b9602a5eb41a6ab066d51a08a4d67d08c62)

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index 7f8eee2..87cbb3f 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit 7f8eee2885899f949eda99281818020301c3c841
+Subproject commit 87cbb3f40576ee913a640acbf49d55e430648a73