Update submodules for v1.2.1

[matthew-white]

This is what I see when I diff locally:

diff --git a/client b/client
index 4f366fd..cdd4294 160000
--- a/client
+++ b/client
@@ -1 +1 @@
-Subproject commit 4f366fd674d83b7f2f156822e5a8d2ceca563b32
+Subproject commit cdd42946d96fdd96e18cfbba94080ac2500de3d8
diff --git a/server b/server
index 24d20de..59556ec 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 24d20de20fdf2e03b55e687542fbc0cae889a9ff
+Subproject commit 59556ecea91f0a25678cd6da0084adb7e66ca099

[lognaturel]

Confirmed getodk/central-frontend@cdd4294 and getodk/central-backend@59556ec look like the last commits we want.

I'm surprised that the frontend merge commit isn't included (3f3c6b66d24413d8196d4a21076aa3ea85a60383) but it shouldn't make a difference.