Fix: Initialize SerialReceiver base in CRSFforArduino constructor

[tzshin]

Hi ZZ-Cat,

I discovered an issue where the CRSFforArduino constructor wasn't properly initializing its SerialReceiver base class with the provided HardwareSerial object. As a result, attempts to specify a different hardware serial port (e.g., new CRSFforArduino(&Serial5);) would default to Serial1, ignoring the user-specified port. This pull request corrects that by ensuring the base class is properly initialized with the user-provided HardwareSerial object.

I've tested the changes using a Teensy 4.0 and an ELRS receiver, confirming the hardware serial port can now be successfully customized. However, as this is my first contribution to any open-source project, I apologize for any possible oversights or missed protocols specific to your project. I'm eager to receive feedback and am fully prepared to make any needed adjustments to meet the project's standards and expectations.

Thank you for considering my contribution. I look forward to any feedback and the opportunity to learn from this experience.

Best regards,
TZShin

[ZZ-Cat]

Thank you for your first contribution to my project, but the fix you're adding here already exists in another Pull Request.

Note

Please take the time to go through my Issues and Pull Request sections to see if your contribution already exists before you submit your Issue or Pull Request.
Currently, this is a bit of an "unspoken rule" and I need to write this in my Contribution Guidelines to negate situations like this in future.

I'm literally about to merge #99 into the Main-Trunk (directly after writing this message).
In that Pull Request, 88be772 provides the same fix as your commit d8ad7dd.

Therefore, your Pull Request is rejected on the grounds of it being a duplicate of the fix that's already provided in another Pull Request.