[TASK] Update UPGRADE.md

UPGRADE.md

-## Version 3 Breaking Changes
-
-- Dropped TYPO3 9 support
-- To optimize performance, the frontendUserRepository was dropped and repository-calls were replaced with direct $queries.
-Hence, the $authenticatedUser variable used in Middlewares, Services and sometime REST-Controllers is now an array. Therefore using the variable as an object doesn't work any longer and needs to be adjusted in external extensions.
+## Version 5 Breaking Changes:
 
-```
-Example:
+- Dropped TYPO3 9 Support
+- Dropped php 7.3 Support
 
-OLD:
-$authenticatedUser->getAuthToken()
+Instead of using an entity name for Plugin registration, we will use the corresponding
+controller for registration, which will be added under classFQN key inside the Entity Configuration:
 
-NEW:
-$authenticatedUser['tx_sgrest_auth_token']
+```php
+$restRegistrationService->registerAccessGroup(
+    'authentication',
+    'SGalinski.sg_rest',
+    'Authentication',
+    [
+       	'authentication' => [
+       	    // Add THIS
+            'classFQN' => \SGalinski\SgRest\Controller\Rest\Authentication\AuthenticationController::class,
+            'read' => 'uid, title'
+        ]
+    ]
+);
 ```
 
 ## Version 4 Breaking Changes:
@@ -27,22 +34,18 @@ NEW:
 RewriteRule ^api/v1/(.*) /index.php?type=1595576052&tx_sgrest[request]=$1 [QSA]
 ```
 
-## Version 5 Breaking Changes:
+## Version 3 Breaking Changes
 
-Instead of using an entity name for Plugin registration, we will use the corresponding
-controller for registration, which will be added under classFQN key inside the Entity Configuration:
+- Dropped TYPO3 9 support
+- To optimize performance, the frontendUserRepository was dropped and repository-calls were replaced with direct $queries.
+Hence, the $authenticatedUser variable used in Middlewares, Services and sometime REST-Controllers is now an array. Therefore using the variable as an object doesn't work any longer and needs to be adjusted in external extensions.
 
-```php
-$restRegistrationService->registerAccessGroup(
-    'authentication',
-    'SGalinski.sg_rest',
-    'Authentication',
-    [
-       	'authentication' => [
-       	    // Add THIS
-            'classFQN' => \SGalinski\SgRest\Controller\Rest\Authentication\AuthenticationController::class,
-            'read' => 'uid, title'
-        ]
-    ]
-);
+```
+Example:
+
+OLD:
+$authenticatedUser->getAuthToken()
+
+NEW:
+$authenticatedUser['tx_sgrest_auth_token']
 ```