ext,tests: Update the testlib download URL for v21.2

Change-Id: I36bb8208485536482f30ef77f6e509379481b5ee
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54467
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/ext/testlib/configuration.py b/ext/testlib/configuration.py
index 95800de..d0fca74 100644
--- a/ext/testlib/configuration.py
+++ b/ext/testlib/configuration.py
@@ -213,7 +213,7 @@
                                                       os.pardir,
                                                       os.pardir))
     defaults.result_path = os.path.join(os.getcwd(), 'testing-results')
-    defaults.resource_url = 'http://dist.gem5.org/dist/develop'
+    defaults.resource_url = 'http://dist.gem5.org/dist/v21-2'
     defaults.resource_path = os.path.abspath(os.path.join(defaults.base_dir,
                                             'tests',
                                             'gem5',