Disambiguate cv::format

Otherwise, this test does not compile with C++20, which includes
std::format.

modules/calib3d/test/test_homography.cpp

@@ -718,12 +718,12 @@ TEST(Calib3d_Homography, not_normalized)
     {
         Mat h = findHomography(p1, p2, method);
         for (auto it = h.begin<double>(); it != h.end<double>(); ++it) {
-            ASSERT_FALSE(cvIsNaN(*it)) << format("method %d\nResult:\n", method) << h;
+            ASSERT_FALSE(cvIsNaN(*it)) << cv::format("method %d\nResult:\n", method) << h;
         }
         if (h.at<double>(0, 0) * ref.at<double>(0, 0) < 0) {
             h *= -1;
         }
-        ASSERT_LE(cv::norm(h, ref, NORM_INF), 1e-8) << format("method %d\nResult:\n", method) << h;
+        ASSERT_LE(cv::norm(h, ref, NORM_INF), 1e-8) << cv::format("method %d\nResult:\n", method) << h;
     }
 }