Use standard repository list URL format for "ESP Async Web Server"

Although either format is valid, the simple web URL is most commonly used in the library repository list. This entry
used the alternative `.git` URL format.

It is hereby brought into alignment with the common convention of the list.

Author: protheeuz

repositories.txt

@@ -7209,5 +7209,5 @@ https://github.com/mgoblin/ArduinoSplashScreen
 https://github.com/senseshift/arduino-ble-serial
 https://github.com/stm32duino/VL53L7CH
 https://github.com/stm32duino/VL53L8CH
-https://github.com/protheeuz/AsyncWebServerESP.git
+https://github.com/protheeuz/AsyncWebServerESP
 https://github.com/JoelJojoP/SimpleIMU