Fix wrong version order

Author: mm0r1

php7-backtrace-bypass/README.md

@@ -6,5 +6,5 @@ This exploit uses a two year old [bug](https://bugs.php.net/bug.php?id=76047) in
   - 7.0 - all versions to date
   - 7.1 - all versions to date
   - 7.2 - all versions to date
-  - 7.3 < 7.4.3 (released 20 Feb 2020)
-  - 7.4 < 7.3.15 (released 20 Feb 2020)
+  - 7.3 < 7.3.15 (released 20 Feb 2020)
+  - 7.4 < 7.4.3 (released 20 Feb 2020)