Update CONTRIBUTING.md

7.1 is EOL; 7.2 is security fixes only.

Author: cmb69

CONTRIBUTING.md

@@ -35,7 +35,7 @@ If you are fixing a bug, then please submit your PR against the lowest actively
 supported branch of PHP that the bug affects (only green branches on
 [the supported version page](https://www.php.net/supported-versions.php) are
 supported). For example, at the time of writing, the lowest supported version is
-PHP 7.2, which corresponds to the `PHP-7.2` branch in Git. Please also make sure
+PHP 7.3, which corresponds to the `PHP-7.3` branch in Git. Please also make sure
 you add a link to the PR in the bug on [the bug tracker](https://bugs.php.net/).
 
 Pull requests implementing RFCs should be submitted against `master`.
@@ -333,8 +333,8 @@ Currently we have the following branches in use:
 | master    | Active development branch for PHP 8.0, which is open for backwards incompatible changes and major internal API changes. |
 | PHP-7.4   | Active development branch for PHP 7.4, which is open for new features and minor internal API changes. |
 | PHP-7.3   | Is used to release the PHP 7.3.x series. This is a current stable version and is open for bugfixes only. |
-| PHP-7.2   | Is used to release the PHP 7.2.x series. This is a current stable version and is open for bugfixes only. |
-| PHP-7.1   | Is used to release the PHP 7.1.x series. This is an old stable version and is open for security fixes only. |
+| PHP-7.2   | Is used to release the PHP 7.2.x series. This is an old stable version and is open for security fixes only. |
+| PHP-7.1   | This branch is closed. |
 | PHP-7.0   | This branch is closed. |
 | PHP-5.6   | This branch is closed. |
 | PHP-5.5   | This branch is closed. |
@@ -348,8 +348,8 @@ Currently we have the following branches in use:
 The next few rules are more of a technical nature:
 
 1. All non-security bugfix changes should first go to the lowest bugfix branch
-   (i.e. 7.2) and then get merged up to all other branches. All security fixes
-   should go to the lowest security fixes branch (i.e 7.1). If a change is not
+   (i.e. 7.3) and then get merged up to all other branches. All security fixes
+   should go to the lowest security fixes branch (i.e 7.2). If a change is not
    needed for later branches (i.e. fixes for features which were dropped from
    later branches) an empty merge should be done.