Rail: specify type for local static variable

fixes a phpstan level 7 error
phpstan doesn't make any assumptions about local static variable types because analysing them would require too much work, apparently.

src/pocketmine/block/Rail.php

@@ -71,6 +71,7 @@ class Rail extends BaseRail{
 	}
 
 	protected function getPossibleConnectionDirectionsOneConstraint(int $constraint) : array{
+		/** @var int[] $horizontal */
 		static $horizontal = [
 			Vector3::SIDE_NORTH,
 			Vector3::SIDE_SOUTH,

tests/phpstan/configs/l7-baseline.neon

@@ -275,11 +275,6 @@ parameters:
 			count: 3
 			path: ../../../src/pocketmine/block/Mycelium.php
 
-		-
-			message: "#^Method pocketmine\\\\block\\\\Rail\\:\\:getPossibleConnectionDirectionsOneConstraint\\(\\) should return array\\<int, true\\> but returns array\\<int\\|string, true\\>\\.$#"
-			count: 1
-			path: ../../../src/pocketmine/block/Rail.php
-
 		-
 			message: "#^Parameter \\#2 \\$x of static method pocketmine\\\\level\\\\generator\\\\object\\\\Tree\\:\\:growTree\\(\\) expects int, float\\|int given\\.$#"
 			count: 2