chore: update kitchen config

Even with the fairly old (3.5) test kitchen version used by the tests,
there are some parameters which have moved to new locations.

Follow the suggestions of `kitchen doctor`.

Author: wyardley

.kitchen.yml

@@ -14,12 +14,15 @@
 ---
 driver:
   name: "terraform"
-  command_timeout: 2700
   verify_version: false
 
 provisioner:
   name: "terraform"
 
+transport:
+  command_timeout: 2700
+  root_module_directory: test/fixtures/shared_vpc
+
 verifier:
   name: terraform
   color: false
@@ -30,8 +33,6 @@ platforms:
 
 suites:
   - name: "shared_vpc"
-    driver:
-      root_module_directory: test/fixtures/shared_vpc
     verifier:
       systems:
         - name: shared_vpc