Update logos for v4 (#6089)

* update v4 logo

* add changeset

* size

* fix on website

* fix on demos

* add changeset

* favicon for demos

* margin on footer logo

* margin bottom to footer logo

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>
Co-authored-by: Ali Abdalla <ali.si3luwa@gmail.com>

.changeset/rude-seas-enjoy.md

@@ -0,0 +1,8 @@
+---
+"@gradio/app": minor
+"@gradio/storybook": minor
+"gradio": minor
+"website": minor
+---
+
+feat:Update logos for v4

README.md

@@ -2,7 +2,7 @@
 
 <div align="center">
 
-[<img src="readme_files/gradio.svg" alt="gradio" width=300>](https://gradio.app)<br>
+[<img src="readme_files/gradio.svg" alt="gradio" width=400>](https://gradio.app)<br>
 <em>Build & share delightful machine learning apps easily</em>
 
 [![gradio-backend](https://github.com/gradio-app/gradio/actions/workflows/backend.yml/badge.svg)](https://github.com/gradio-app/gradio/actions/workflows/backend.yml)