[3.11] gh-111929: Fix regrtest --pgo: test_str => test_unicode (GH-111938) (#111940)

gh-111929: Fix regrtest --pgo: test_str => test_unicode (GH-111938)

test_unicode was renamed to test_str in Python 3.13, but Python 3.12
still uses test_unicode name.
(cherry picked from commit 5f42a2b)

Co-authored-by: Victor Stinner <[email protected]>

Author: miss-islington

Lib/test/libregrtest/pgo.py

@@ -42,10 +42,10 @@
     'test_set',
     'test_sqlite3',
     'test_statistics',
-    'test_str',
     'test_struct',
     'test_tabnanny',
     'test_time',
+    'test_unicode',
     'test_xml_etree',
     'test_xml_etree_c',
 ]