docker build fails with golang versions later than 1.12

[lle0x]

Description

docker build fails when golang docker image used to build this project is later than 1.12

Steps to reproduce the issue:

1. Edit https://github.com/freedomwatchers/docker-flow-proxy/blob/develop/Dockerfile
2. Change line 1, from "FROM golang:1.12-alpine AS build" to "FROM golang:1.13-alpine AS build"
3. Repeat same change with newer versions (not beta) from https://hub.docker.com/_/golang

Describe the results you received:

--- FAIL: TestLoggingUnitTestSuite (10.28s)
    --- FAIL: TestLoggingUnitTestSuite/Test_StartLogging_OutputsSyslogToStdOut (10.27s)
        logging_test.go:51: 
            	Error Trace:	logging_test.go:51
            	Error:      	Should be true
            	Test:       	TestLoggingUnitTestSuite/Test_StartLogging_OutputsSyslogToStdOut
FAIL
coverage: 100.0% of statements
FAIL	github.com/docker-flow/docker-flow-proxy/logging	10.284s
?   	github.com/docker-flow/docker-flow-proxy/metrics	[no test files]
ok  	github.com/docker-flow/docker-flow-proxy/proxy	1.231s	coverage: 89.3% of statements
ok  	github.com/docker-flow/docker-flow-proxy/server	0.309s	coverage: 97.7% of statements
FAIL
The command '/bin/sh -c set -x     && apk add --update --no-cache --no-progress git g++     && go get -d -v     && go test --cover ./... --run UnitTest     && go build -v -o docker-flow-proxy' returned a non-zero code: 1

Describe the results you expected:

ok  	github.com/docker-flow/docker-flow-proxy	0.573s	coverage: 80.9% of statements
ok  	github.com/docker-flow/docker-flow-proxy/actions	0.193s	coverage: 92.2% of statements
ok  	github.com/docker-flow/docker-flow-proxy/integration_tests	0.004s	coverage: 0.0% of statements [no tests to run]
ok  	github.com/docker-flow/docker-flow-proxy/logging	0.106s	coverage: 100.0% of statements
?   	github.com/docker-flow/docker-flow-proxy/metrics	[no test files]
ok  	github.com/docker-flow/docker-flow-proxy/proxy	1.146s	coverage: 89.3% of statements
ok  	github.com/docker-flow/docker-flow-proxy/server	0.831s	coverage: 97.7% of statements

Additional information you deem important (e.g. issue happens only occasionally):

Additional environment details (AWS, VirtualBox, physical, etc.):

docker -v
Docker version 19.03.6, build 369ce74a3c