Upgrade to Insta master to get bugfix.

Map sorting in Insta was previously not recursive.
As of this PR, it is!
https://github.com/mitsuhiko/insta/pull/80

Since it hasn't made it into a release yet, but is
important for Rojo to have snapshot determinism,
we're moving temporarily to depend on Insta via Git.

rojo-test/serve-test-snapshots/serve_test__add_folder_subscribe.snap

@@ -4,16 +4,16 @@ expression: "subscribe_response.intern_and_redact(&mut redactions, ())"
 ---
 messageCursor: 1
 messages:
-  - removedInstances: []
-    addedInstances:
+  - addedInstances:
       id-3:
-        Id: id-3
-        Parent: id-2
-        Name: my-new-folder
-        ClassName: Folder
-        Properties: {}
         Children: []
+        ClassName: Folder
+        Id: id-3
         Metadata:
           ignoreUnknownInstances: false
+        Name: my-new-folder
+        Parent: id-2
+        Properties: {}
+    removedInstances: []
     updatedInstances: []
 sessionId: id-1