Replace obsolete references to App baseURL and getApp by DI

src/Module/Api/Mastodon/Instance.php

@@ -17,6 +17,6 @@ class Instance extends Api
 	 */
 	public static function rawContent(array $parameters = [])
 	{
-		System::jsonExit(InstanceEntity::get(self::getApp()));
+		System::jsonExit(InstanceEntity::get());
 	}
 }

src/Module/HoverCard.php

@@ -16,7 +16,7 @@ class HoverCard extends BaseModule
 {
 	public static function rawContent(array $parameters = [])
 	{
-		$a = self::getApp();
+		$a = DI::app();
 
 		if ((local_user()) && ($parameters['action'] ?? '') === 'view') {
 			// A logged in user views a profile of a user

src/Module/Security/OpenID.php

@@ -52,7 +52,7 @@ class OpenID extends BaseModule
 					// successful OpenID login
 					$session->remove('openid');
 
-					DI::auth()->setForUser(self::getApp(), $user, true, true);
+					DI::auth()->setForUser(DI::app(), $user, true, true);
 
 					// just in case there was no return url set
 					// and we fell through