Fix PacktPub book covers

README.md

@@ -61,7 +61,7 @@ Go in Action introduces the Go language, guiding you from inquisitive developer
 
 ### [Go Programming Blueprints - 2nd Ed.](https://www.packtpub.com/application-development/go-programming-blueprints-second-edition)
 
-<img src="https://www.packtpub.com/media/catalog/product/cache/e4d64343b1bc593f1c5348fe05efa4a6/b/0/b05569.png" width="120px"/>
+<img src="https://static.packt-cdn.com/products/9781786468949/cover/smaller" width="120px"/>
 
 This book shows you how to build powerful systems and drops you into real-world situations. Scale, performance, and high availability lie at the heart of our projects, and the lessons learned throughout this book will arm you with everything you need to build world-class solutions.
 
@@ -182,7 +182,7 @@ Tested, easy-to-adapt code examples illuminate every step of Go development, hel
 
 ### [Go Design Patterns](https://www.packtpub.com/application-development/go-design-patterns)
  
-<img src="https://www.packtpub.com/media/catalog/product/cache/e4d64343b1bc593f1c5348fe05efa4a6/b/0/b05557.png" width="120px"/>
+<img src="https://static.packt-cdn.com/products/9781786466204/cover/smaller" width="120px"/>
 
 Learn idiomatic, efficient, clean, and extensible Go design and concurrency patterns by using TDD.
 
@@ -210,7 +210,7 @@ Hands-On Dependency Injection in Go takes a pragmatic approach and focuses heavi
 
 ### [Hands-On Software Engineering with Golang](https://www.packtpub.com/gb/programming/hands-on-software-engineering-with-golang)
 
-<img src="https://www.packtpub.com/media/catalog/product/cache/ecd051e9670bd57df35c8f0b122d8aea/9/7/9781838554491-original.png" width="120px"/>
+<img src="https://static.packt-cdn.com/products/9781838554491/cover/smaller" width="120px"/>
 
 This Golang book distills industry best practices for writing lean Go code that is easy to test and maintain, and helps you to explore its practical implementation by creating a multi-tier application called Links ‘R’ Us from scratch. You’ll be guided through all the steps involved in designing, implementing, testing, deploying, and scaling an application. Starting with a monolithic architecture, you’ll iteratively transform the project into a service-oriented architecture (SOA) that supports the efficient out-of-core processing of large link graphs. 
 
@@ -281,7 +281,7 @@ This course is an invaluable resource to help you understand Go's powerful featu
 
 ### [Building Microservices with Go](https://www.packtpub.com/application-development/building-microservices-go)
 
-<img src="https://www.packtpub.com/media/catalog/product/cache/e4d64343b1bc593f1c5348fe05efa4a6/b/0/b05528.png" width="120px"/>
+<img src="https://static.packt-cdn.com/products/9781786468666/cover/smaller" width="120px"/>
 
 Whether you are planning a new application or working in an existing monolith, this book will explain and illustrate with practical examples how teams of all sizes can start solving problems with microservices. It will help you understand Docker and Docker-Compose and how it can be used to isolate microservice dependencies and build environments. We finish off by showing you various techniques to monitor, test, and secure your microservices.