Replace Travis with Github workflows (#18)

* Replace Travis with Github workflows

* Remove ruby 2.5

Author: laurynas-convertapi

.github/workflows/main.yml

@@ -0,0 +1,26 @@
+name: Build
+on: [push,pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby-version:
+          - 2.0
+          - 2.6
+          - 2.7
+          - 3.0
+          - ruby-head
+          - jruby-9.1
+          - jruby-head
+    name: Ruby ${{ matrix.ruby-version }} sample
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+#          bundler-cache: true
+      - run: bundle install
+      - env:
+          CONVERT_API_SECRET: ${{ secrets.CONVERTAPI_SECRET }}
+        run: bundle exec rake spec

.travis.yml

@@ -2,7 +2,9 @@
 
 
 [![Gem](https://img.shields.io/gem/v/convert_api.svg)](https://rubygems.org/gems/convert_api)
-[![Build Status](https://secure.travis-ci.org/ConvertAPI/convertapi-ruby.svg)](http://travis-ci.org/ConvertAPI/convertapi-ruby)
+[![Build Status](https://github.com/ConvertAPI/convertapi-ruby/actions/workflows/main.yml/badge.svg)](https://github.com/ConvertAPI/convertapi-ruby/actions)
+[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
+
 
 ## Convert your files with our online file conversion API