Fix typo: Update footer year from 2022 to 2023

Author: lamanda20

README.md

@@ -4,6 +4,7 @@
 
 A calculator that calculates simple interest given principal, annual rate of interest and time period in years.
 
+
 ```
 Input:
    p, principal amount
@@ -13,4 +14,4 @@ Output
    simple interest = p*t*r
 ```
 
-_© 2022 XYZ, Inc._
+_© 2023 XYZ, Inc._