Added missing spinner test

test/spinner-test.cpp

+#include <cif++/utilities.hpp>
+
+#include <random>
+#include <thread>
+
+int main()
+{
+	cif::progress_bar pb(10, "test");
+
+	std::random_device rd;
+    std::mt19937 gen(rd());
+    std::uniform_int_distribution<> distrib(100, 1000);
+ 
+	for (int i = 0; i < 10; ++i)
+	{
+		std::this_thread::sleep_for(std::chrono::milliseconds(distrib(gen)));
+
+		pb.message("step " + std::to_string(i));
+		pb.consumed(1);
+	}
+
+	return 0;
+}
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