Fix clang-format issues: add newlines at end of files

Author: PauLopNun

src/main/java/com/thealgorithms/sorts/AmericanFlagSort.java

@@ -60,4 +60,4 @@ private <T extends Comparable<T>> int getDigit(T element, int digitIndex) {
         }
         return str.charAt(str.length() - 1 - digitIndex);
     }
-}
+}

src/test/java/com/thealgorithms/sorts/AmericanFlagSortTest.java

@@ -5,4 +5,4 @@ public class AmericanFlagSortTest extends SortingAlgorithmTest {
     SortAlgorithm getSortAlgorithm() {
         return new AmericanFlagSort();
     }
-}
+}