bpo-33988: Fix test_warnings using -W error (GH-7985)

Use DeprecationWarning instead of PendingDeprecationWarning.
diff --git a/Lib/test/test_platform.py b/Lib/test/test_platform.py
index 5f1e28a..d3b77eb 100644
--- a/Lib/test/test_platform.py
+++ b/Lib/test/test_platform.py
@@ -265,7 +265,7 @@
                 'ignore',
                 r'dist\(\) and linux_distribution\(\) '
                 'functions are deprecated .*',
-                PendingDeprecationWarning,
+                DeprecationWarning,
             )
             res = platform.dist()
 
@@ -341,7 +341,7 @@
                         'ignore',
                         r'dist\(\) and linux_distribution\(\) '
                         'functions are deprecated .*',
-                        PendingDeprecationWarning,
+                        DeprecationWarning,
                     )
                     distname, version, distid = platform.linux_distribution()
 
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 7bbaa9f..d80e8d3 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -4145,7 +4145,7 @@
                 'ignore',
                 r'dist\(\) and linux_distribution\(\) '
                 'functions are deprecated .*',
-                PendingDeprecationWarning,
+                DeprecationWarning,
             )
             for name, func in plats.items():
                 plat = func()