final fix to quiver6

Author: matthew-hennefarth

examples/vector_fields/quiver/quiver_6.cpp

@@ -5,9 +5,9 @@ int main() {
     using namespace matplot;
     auto [x, y] = meshgrid(iota(-2.5, 0.25, 2.5), iota(-2.5, 0.25, 2.5));
     vector_2d u =
-        transform(x, y, [](double x, double y) { return cos(x)*sin(x + y); });
+        transform(x, y, [](double x, double y) { return cos(x) * sin(x + y); });
     vector_2d v =
-        transform(x, y, [](double x, double y) { return sin(y)*cos(x + y); });
+        transform(x, y, [](double x, double y) { return sin(y) * cos(x + y); });
 
     vector_2d m =
         transform(u, v, [](double u, double v) { return sqrt(u * u + v * v); });