test_houghlines: Fix C++20 compatibility

C++20 made it invalid to use simple-template-ids for constructors and destructors: https://eel.is/c++draft/diff.cpp17.class#2
GCC 11 and later throw an error on this, with the unhelpful message `expected unqualified-id before ')' token`. This PR fixes the problem.

modules/imgproc/test/test_houghlines.cpp

@@ -53,7 +53,7 @@ struct SimilarWith
     T value;
     float theta_eps;
     float rho_eps;
-    SimilarWith<T>(T val, float e, float r_e): value(val), theta_eps(e), rho_eps(r_e) { };
+    SimilarWith(T val, float e, float r_e): value(val), theta_eps(e), rho_eps(r_e) { };
     bool operator()(const T& other);
 };