release 0.3.1

For the external contribution, I worked on a CI/CD area for this repo. The pull request address is https://github.com/kaspanet/kaspad/pull/1130.

This repo is using Jenkins to build and test, they want to try something new. I suggest that they can try Github actions which is awesome for this kind of job.

I added a go.yaml file to complete this task. The code I added:

name: Go

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  build:
    strategy:
      matrix:
        go-version: [1.15.x]
        os: [ubuntu-latest, macos-latest, windows-latest]
    runs-on: ${{ matrix.os }}
    steps:
    - name: Set up Go 1.x
      uses: actions/setup-go@v2
      with:
        go-version: ^1.15

    - name: Check out code into the Go module directory
      uses: actions/checkout@v2

    - name: Build
      run: go build -v .

    - name: Test
      run: go test -v .