chore(build): switch to go 1.13

.circleci/config.yml

@@ -28,7 +28,7 @@ default_environment: &default_environment
 executors:
   golang:
     docker:
-      - image: circleci/golang:1.12
+      - image: circleci/golang:1.13
     working_directory: ~/ipfs/go-ipfs
     environment:
       <<: *default_environment

Dockerfile

-FROM golang:1.12.9-buster
+FROM golang:1.13.4-buster
 LABEL maintainer="Steven Allen <steven@stebalien.com>"
 
 ENV SRC_DIR /go-ipfs

README.md

@@ -149,7 +149,7 @@ PS> scoop install go-ipfs
 
 ### Build from Source
 
-go-ipfs's build system requires Go 1.12 and some standard POSIX build tools:
+go-ipfs's build system requires Go 1.13 and some standard POSIX build tools:
 
 * GNU make
 * Git

go.mod

@@ -107,4 +107,4 @@ require (
 	gopkg.in/cheggaaa/pb.v1 v1.0.28
 )
 
-go 1.12
+go 1.13

mk/golang.mk

 # golang utilities
-GO_MIN_VERSION = 1.12
+GO_MIN_VERSION = 1.13
 export GO111MODULE=on