Changed age variable declaration from const to let to allow reassignment

Author: Maryanne-K

Sprint-1/2-mandatory-errors/1.js

@@ -1,4 +1,5 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+// use let instead of const to declare the age variable, as const variables cannot be reassigned.