util-gem5art: Fix the artifact test with incorrect git repo

The gem5art tests add the current repository as an artifact. Previously
this repository was called "gem5art". Since moving to the gem5 repo, it
is now called "gem5". Therefore the test checking the repository name
needed fixed.

Note: We need a better solution for testing gem5art's git functionality.
Using the current repository is not stable, as this fix shows. Noted
in Jira: https://gem5.atlassian.net/browse/GEM5-1013.

Change-Id: I017ff039ccb1c0a290f9aa1a09bd738c1820f88f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47220
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>

util/gem5art/artifact/tests/test_artifact.py

@@ -92,7 +92,7 @@ class TestGit(unittest.TestCase):
     def test_origin(self):
         git = artifact.artifact.getGit(Path("."))
         self.assertTrue(
-            git["origin"].endswith("gem5art"), "Origin should end with gem5art"
+            git["origin"].endswith("gem5"), "Origin should end with gem5art"
         )