Update composer dev dependencies

tests/phpstan/configs/actual-problems.neon

@@ -948,6 +948,12 @@ parameters:
 			count: 1
 			path: ../../../src/plugin/PluginDescription.php
 
+		-
+			message: '#^Property pocketmine\\plugin\\PluginDescription\:\:\$srcNamespacePrefix \(string\) does not accept mixed\.$#'
+			identifier: assign.propertyType
+			count: 1
+			path: ../../../src/plugin/PluginDescription.php
+
 		-
 			message: '#^Cannot call method addChild\(\) on pocketmine\\permission\\Permission\|null\.$#'
 			identifier: method.nonObject
@@ -990,6 +996,12 @@ parameters:
 			count: 1
 			path: ../../../src/scheduler/TaskScheduler.php
 
+		-
+			message: '#^Possibly invalid array key type mixed\.$#'
+			identifier: offsetAccess.invalidOffset
+			count: 1
+			path: ../../../src/thread/ThreadManager.php
+
 		-
 			message: '#^Cannot access offset string on mixed\.$#'
 			identifier: offsetAccess.nonOffsetAccessible