remove final from class declaration in saddle-points exercise

exercises/saddle-points/src/main/java/Matrix.java

@@ -1,4 +1,4 @@
-final class Matrix {
+class Matrix {
 
 
 

exercises/saddle-points/src/main/java/MatrixCoordinate.java

@@ -1,4 +1,4 @@
-final class MatrixCoordinate {
+class MatrixCoordinate {
 
   private final int row;