add test for pre C++20 includes

tests/LegacyInclude.cpp

@@ -0,0 +1,33 @@
+#include <doctest.h>
+
+#include <opencv2/core.hpp>
+#include <opencv2/videoio.hpp>
+
+#include <filesystem>
+
+#include <FairyCam/AnyCamera.hpp>
+
+using namespace FairyCam;
+
+TEST_SUITE("AnyCamera")
+{
+    TEST_CASE_TEMPLATE("create", T, cv::VideoCapture, DirectoryTriggerCamera,
+                       FileCamera, DirectoryTriggerCamera, HttpCamera)
+    {
+        AnyCamera cam = AnyCamera::create<T>();
+    }
+
+    TEST_CASE("dynamicCast")
+    {
+        AnyCamera cam = AnyCamera::create<FileCamera>();
+        REQUIRE_FALSE(cam.dynamicCast<DirectoryCamera>());
+        auto fileCam = cam.dynamicCast<FileCamera>();
+        REQUIRE(fileCam);
+        FileCamera &cam_ref = *fileCam;
+        REQUIRE_FALSE(cam.isOpened());
+        REQUIRE_FALSE(cam_ref.isOpened());
+        cam_ref.open(0, 0, {});
+        REQUIRE(cam.isOpened());
+        REQUIRE(cam_ref.isOpened());
+    }
+}