Update minimum viable Go version for building

README.md

@@ -45,7 +45,7 @@ to get started with one of Sensu's [supported packages](https://docs.sensu.io/se
 ### Building from source
 
 The various components of Sensu Go can be manually built from this repository.
-You will first need [Go >= 1.13](https://golang.org/doc/install#install)
+You will first need [Go >= 1.16](https://golang.org/doc/install#install)
 installed. Then, you should clone this repository **outside** of the GOPATH
 since Sensu Go uses [Go Modules](https://github.com/golang/go/wiki/Modules):
 ```