fix(docs): Required Go version is bumped to 1.13

Signed-off-by: Federico Barcelona <[email protected]>

Author: tembleking

README.md

@@ -12,7 +12,7 @@ Requirements
 ------------
 
 -	[Terraform](https://www.terraform.io/downloads.html) 0.12.x
--	[Go](https://golang.org/doc/install) 1.12 (to build the provider plugin)
+-	[Go](https://golang.org/doc/install) 1.13 (to build the provider plugin)
 
 Building The Provider
 ---------------------