Use Github workflows to compile examples and spell check (replaces Travis CI)

Author: sandeepmistry

.github/workflows/compile-examples.yml

@@ -0,0 +1,21 @@
+name: Compile Examples
+on: [push, pull_request]
+jobs:
+ build:
+   runs-on: ubuntu-latest
+
+   strategy:
+     matrix:
+       fqbn: [
+         "arduino:samd:mkrwifi1010",
+         "arduino:megaavr:uno2018"
+       ]
+
+   steps:
+     - uses: actions/checkout@v1
+       with:
+         fetch-depth: 1
+     - uses: arduino/actions/libraries/compile-examples@master
+       with:
+         fqbn: ${{ matrix.fqbn }}
+         libraries: WiFiNINA

.github/workflows/spell-check.yml

@@ -0,0 +1,11 @@
+name: Spell Check
+on: [push, pull_request]
+jobs:
+ build:
+   runs-on: ubuntu-latest
+
+   steps:
+     - uses: actions/checkout@v1
+       with:
+         fetch-depth: 1
+     - uses: arduino/actions/libraries/spell-check@master

.travis.yml

@@ -1,7 +1,7 @@
 = ArduinoMqttClient Library for Arduino =
 
+image:https://github.com/arduino-libraries/ArduinoMqttClient/workflows/Compile%20Examples/badge.svg["Compile Examples Status", link="https://github.com/arduino-libraries/ArduinoMqttClient/actions?workflow=Compile+Examples"] image:https://github.com/arduino-libraries/ArduinoMqttClient/workflows/Spell%20Check/badge.svg["Spell Check Status", link="https://github.com/arduino-libraries/ArduinoMqttClient/actions?workflow=Spell+Check"]
 
-image:https://travis-ci.org/arduino-libraries/ArduinoMqttClient.svg?branch=master["Build Status", link="https://travis-ci.org/arduino-libraries/ArduinoMqttClient"]
 
 Allows you to send and receive MQTT messages using Arduino.