[BUGFIX] [Hacker Rank]: Project Euler #1: Multiples of 3 and 5. Coverage increased.

Author: Gonzalo Diaz

src/tests/unit/lib/hackerrank/projecteuler/euler001.testcases.json

@@ -1,5 +1,6 @@
 [
   { "a": 3, "b": 5, "n": 10, "expected": 23 },
+  { "a": 5, "b": 3, "n": 10, "expected": 23 },
   { "a": 3, "b": 5, "n": 100, "expected": 2318 },
   { "a": 3, "b": 5, "n": 1000, "expected": 233168 }
 ]