feat: specify Go version

[mmailhos]

This would fix errors when parsing go.mod due to a Go version mismatch.
Ref: #31

[mmailhos]

Actually Github Actions does not support build-arg.
Feature Request
Docker Actions runs syntax

I'll be doing some more test and see if we can have a work-around.

[mmailhos]

Because Github Action does not support build-arg, I have moved the Go binary install (from initially Docker image) to entrypoint.sh.

Removed initial commit.

Made Go version required with default to 1.14.2.

[sue445]

1.14.2 is the latest version at this time, but not latest version in future. I don't want to release action every time there is a new go version.

This is hard coding in another sense.

I prefer getting the latest version when performing an action. I think it's natural to use the latest version if go_version was omitted

This is a snippet to get the latest version of Go.

$ curl -s https://api.github.com/repos/golang/go/git/refs/tags | jq --raw-output '.[].ref | select(test("^refs/tags/go[0-9.]+$"))' | tail -n 1 | sed 's!refs/tags/go!!'
1.14.2

[mmailhos]

Thanks for the command, it's much better

[sue445]

LGTM!

[sue445]

I released as v1.4.0