Apple has made following changes so download new certificate developer.apple.com
renewed certificate and place it as below screen shots .In the keychain as below screen shots click on system and then certificate. Delete the expired certificate . Then drag and drop the AppleWWDRCA.cer that you downloaded from above link
Apple Worldwide Developer Relations Intermediate Certificate Expiration
To help protect customers and developers, we require that all third
party apps, passes for Apple Wallet, Safari Extensions, Safari Push
Notifications, and App Store purchase receipts are signed by a trusted
certificate authority. The Apple Worldwide Developer Relations
Certificate Authority issues the certificates you use to sign your
software for Apple devices, allowing our systems to confirm that your
software is delivered to users as intended and has not been modified.
The Apple Worldwide Developer Relations Certification Intermediate
Certificate expires soon and we've issued a renewed certificate that
must be included when signing all new Apple Wallet Passes, push
packages for Safari Push Notifications, and Safari Extensions starting
February 14, 2016.
While most developers and users will not be affected by the
certificate change, we recommend that all developers download and
install the renewed certificate on their development systems and
servers as a best practice. All apps will remain available on the App
Store for iOS, Mac, and Apple TV.
Since different methods can be used for validating receipts and
delivering remote notifications, we recommend that you test your
services to ensure no implementation-specific issues exist. Your apps
may experience receipt verification failure if the receipt checking
code makes incorrect assumptions about the certificate. Make sure that
your code adheres to the Receipt Validation Programming Guide and
resolve all receipt validation issues before February 14, 2016.