[CI] Adicionar Github Actions

[gitrubs]

Descrição

Adicionar workflow básico do github actions com teste executado pelo gradle

Requisitos

Máquina: ubuntu-latest
Versão do Java: 1.8

Sintaxe de exemplo

name: Run Tests
on: [push]
jobs:
  test:
    name: Test Job
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Set up JDK 1.8
      uses: actions/setup-java@v1
      with:
        java-version: 1.8
    - name: Grant execute permission for gradlew
      run: chmod +x gradlew
    - name: Gradle test
      run: gradlew test