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/config_pl.xml

@@ -2,7 +2,7 @@
 <module>
     <name>pshowsso</name>
     <displayName><![CDATA[SSO Single Sign-On]]></displayName>
-    <version><![CDATA[1.3.8]]></version>
+    <version><![CDATA[1.3.9]]></version>
     <description><![CDATA[Allow customers to log in via social media and other third-party services.]]></description>
     <author><![CDATA[PrestaShow.com]]></author>
     <tab><![CDATA[other]]></tab>