[3.10] bpo-25130: Add calls of gc.collect() in tests to support PyPy (GH-28005) (GH-28027)

(cherry picked from commit 2a8127cafe1d196f858a3ecabf5f1df3eebf9a12)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
index ba3d233..f1ca8cb 100644
--- a/Lib/test/test_copy.py
+++ b/Lib/test/test_copy.py
@@ -7,6 +7,7 @@
 from operator import le, lt, ge, gt, eq, ne
 
 import unittest
+from test import support
 
 order_comparisons = le, lt, ge, gt
 equality_comparisons = eq, ne
@@ -805,6 +806,7 @@ class C(object):
         self.assertEqual(v[c], d)
         self.assertEqual(len(v), 2)
         del c, d
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
         x, y = C(), C()
         # The underlying containers are decoupled
@@ -834,6 +836,7 @@ def __init__(self, i):
         self.assertEqual(v[a].i, b.i)
         self.assertEqual(v[c].i, d.i)
         del c
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
 
     def test_deepcopy_weakvaluedict(self):
@@ -857,6 +860,7 @@ def __init__(self, i):
         self.assertIs(t, d)
         del x, y, z, t
         del d
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
 
     def test_deepcopy_bound_method(self):