added colors to button and added icon

[deytulsi18]

Hello Anuj bhaiya, I am your big fan. I learnt about GIT from your Apni Kaksha video, I learnt a few android basics and also following your android devloptment course on your channel "Anuj Bhaiya". so I made some changes to your Birthday Wishing app as listed below:-

1. Changed the UI color from blue to red,
2. added icon ,
3. updated button to rounded corners with red color(gradient)

So, bhaiya this would be my very first open source contribution, please accept the pull request.

And thanks a lot for teaching me GIT and github , please continue to help us leaning more.

[deytulsi18]

Bhaiya I have one more request please accept my connect request on LinkedIn. https://www.linkedin.com/in/deytulsi18