Merge pull request #26 from rrbox/hotfix/physicsbody

physicsBody メソッドにアクセスできないバグを修正

Sources/SKNodeBuilder/Builder.swift

@@ -42,7 +42,7 @@ final public class Builder<Body: SKNode>: NSObject {
         self.body.name = name
         return self
     }
-    @discardableResult func physicsBody(_ physicsBody: SKPhysicsBody?) -> Self {
+    @discardableResult public func physicsBody(_ physicsBody: SKPhysicsBody?) -> Self {
         self.body.physicsBody = physicsBody
         return self
     }