Bump golang to v1.13.4

.travis.yml

@@ -1,8 +1,7 @@
-sudo: required
 language: go
 go:
-- 1.13
+- 1.13.x
 services:
 - docker
 script:
-- env GO111MODULE=on make test
+- make test

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.13.0 AS build
+FROM golang:1.13.4 AS build
 WORKDIR /go/src/github.com/zricethezav/gitleaks
 COPY . .
 RUN GO111MODULE=on CGO_ENABLED=0 go build -o bin/gitleaks *.go
@@ -14,4 +14,3 @@ ENTRYPOINT ["gitleaks"]
 # docker run --rm --name=gitleaks gitleaks --repo=https://github.com/zricethezav/gitleaks
 
 # This will check for secrets in https://github.com/zricethezav/gitleaks
-

go.mod

@@ -1,6 +1,6 @@
 module github.com/zricethezav/gitleaks
 
-go 1.12
+go 1.13
 
 require (
 	github.com/BurntSushi/toml v0.3.1