Update README.md

Author: vfalies

README.md

@@ -12,7 +12,7 @@ docker run --rm -v $(pwd):/app vfac/php7compatibility <version> <option> <path>
 
 ### <version>
 
-PHP Version used to check code compatibility: 7.0, 7.1, 7.2
+PHP Version used to check code compatibility: 7.0, 7.1, 7.2, 7.3
 
 For instance to check code of the current directory in PHP version 7.1 :