Dark mode logo (browser-use#184)

* adding dark mode logo

* Update README.md

No flashbang

Author: Cfomodz

README.md

@@ -1,4 +1,8 @@
-<img src="./static/browser-use.png" alt="Browser Use Logo" width="full"/>
+<picture>
+  <source media="(prefers-color-scheme: dark)" srcset="./static/browser-use-dark.png">
+  <source media="(prefers-color-scheme: light)" srcset="./static/browser-use.png">
+  <img alt="Shows a black Browser Use Logo in light color mode and a white one in dark color mode." src="./static/browser-use.png"  width="full">
+</picture>
 
 <br/>