Fix exact floating-point comparison causing flaky test (#9021)

This triggered semi-reliably on Windows with all optional packages
installed, with the output different by 2 ULP.  It's a floating-point
equality check, so what we care about asserting is approximate equality,
not exact.

test/python/opflow/test_aer_pauli_expectation.py

@@ -279,12 +279,12 @@ def test_expectation_with_coeff(self):
         with self.subTest("integer coefficients"):
             exp = 3 * ~StateFn(X) @ (2 * Minus)
             target = self.sampler.convert(self.expect.convert(exp)).eval()
-            self.assertEqual(target, -12)
+            self.assertAlmostEqual(target, -12)
 
         with self.subTest("complex coefficients"):
             exp = 3j * ~StateFn(X) @ (2j * Minus)
             target = self.sampler.convert(self.expect.convert(exp)).eval()
-            self.assertEqual(target, -12j)
+            self.assertAlmostEqual(target, -12j)
 
 
 if __name__ == "__main__":