OsmoGSMTester: Update import test->testenv

Latest changes in osmo-gsm-tester require this import change.

Depends on: osmo-gsm-tester I520bd046cb09042b5567d967f951f050e4e02e85

Change-Id: I0f7f7d0353014b7ef8a0c5a7707c91b2613be79a
diff --git a/doc/manuals/chapters/intro.adoc b/doc/manuals/chapters/intro.adoc
index 55f1a5e..14daba4 100644
--- a/doc/manuals/chapters/intro.adoc
+++ b/doc/manuals/chapters/intro.adoc
@@ -161,7 +161,7 @@
 
 ----
 #!/usr/bin/env python3
-from osmo_gsm_tester.test import *
+from osmo_gsm_tester.testenv import *
 
 hlr = suite.hlr()
 bts = suite.bts()