Add submission # 7421

#7421

Author: ArduinoBot

registry.txt

@@ -8734,3 +8734,4 @@ https://github.com/TUDA-MUST/Resense-HEX.git|Contributed|Resense HEX
 https://github.com/dudmoryo-cyber/TTP229_keypad.git|Contributed|TTP229 Keypad Driver
 https://github.com/LEKPCSTEAM/ESP32-OTA-Client.git|Contributed|ESP32-OTA-Client
 https://github.com/cpei2025/ESPNowAdhoc.git|Contributed|ESPNowAdhoc
+https://github.com/BojanJurca/Thread-safe-ping-Arduino-library-for-ESP32.git|Contributed|ThreadSafePing