Merge branch '6.4' into 7.0

* 6.4:
  load function only if not loaded before
  [VarExporter] Remove obsolete PHP version check
  [PsrHttpMessageBridge] Streamline README.md with other components
  Bump Symfony version to 6.2.15
  Update VERSION for 6.2.14
  Update CHANGELOG for 6.2.14
  Bump Symfony version to 6.3.4
  Update VERSION for 6.3.3
  Update CHANGELOG for 6.3.3
  Bump Symfony version to 5.4.28
  Update VERSION for 5.4.27
  Update CONTRIBUTORS for 5.4.27
  Update CHANGELOG for 5.4.27

Author: derrabus

README.md

@@ -6,14 +6,8 @@ Provides integration for PSR7.
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/psr7.html)
-
-Running the tests
------------------
-
-If you want to run the unit tests, install dev dependencies before
-running PHPUnit:
-
-    $ cd path/to/Symfony/Bridge/PsrHttpMessage/
-    $ composer.phar install
-    $ phpunit
+ * [Documentation](https://symfony.com/doc/current/components/psr7.html)
+ * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+ * [Report issues](https://github.com/symfony/symfony/issues) and
+   [send Pull Requests](https://github.com/symfony/symfony/pulls)
+   in the [main Symfony repository](https://github.com/symfony/symfony)