Add ESP32 board to "Compile Examples" CI workflow

ESP32 support has been added to the library, so the examples compilation smoke test should be done for this architecture
as well.

Author: per1234

.github/workflows/compile-examples.yml

@@ -43,6 +43,8 @@ jobs:
             platform-name: arduino:mbed
           - fqbn: "esp8266:esp8266:huzzah"
             platform-name: esp8266:esp8266
+          - fqbn: "esp32:esp32:esp32"
+            platform-name: esp32:esp32
 
         # Make board type-specific customizations to the matrix jobs
         include:
@@ -65,6 +67,12 @@ jobs:
               # Install ESP8266 platform via Boards Manager
               - name: esp8266:esp8266
                 source-url: https://arduino.esp8266.com/stable/package_esp8266com_index.json
+          - board:
+              platform-name: esp32:esp32
+            platforms: |
+              # Install ESP32 platform via Boards Manager
+              - name: esp32:esp32
+                source-url: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
 
     steps:
       - uses: actions/checkout@v1