fix missing extension in workflow file

Author: Richard Unger

.github/workflows/ccpp.yml

@@ -59,7 +59,7 @@ jobs:
 
           - arduino-boards-fqbn: esp32:esp32:esp32s2 # esp32s2
             platform-url: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json
-            sketch-names: bldc_driver_3pwm_standalone.ino, stepper_driver_2pwm_standalone.ino, stepper_driver_4pwm_standalone 
+            sketch-names: bldc_driver_3pwm_standalone.ino,stepper_driver_2pwm_standalone.ino,stepper_driver_4pwm_standalone.ino
 
           - arduino-boards-fqbn: esp32:esp32:esp32s3 # esp32s3
             platform-url: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json