Add Symfony Deprecation Contracts package

- Created CHANGELOG.md to maintain version history.
- Added README.md with usage instructions for the trigger_deprecation() function.
- Initialized composer.json for the Symfony Deprecation Contracts library, specifying dependencies and autoloading.

modules/pshowsso/vendor/autoload_.php

@@ -21,4 +21,4 @@ if (file_exists(__DIR__ . '/../deps/autoload.php')) {
 }
 
 require_once __DIR__ . '/composer/autoload_real.php';
-return ComposerAutoloaderInitc0ed3f98dd7049a39f692ffc2529a248::getLoader();
+return ComposerAutoloaderInitec1a73316f7c92d3ccef54b8d0420c77::getLoader();