Fix readme typo

Author: jjw24

README.md

@@ -364,7 +364,7 @@ Get in touch if you like to join the Flow-Launcher Team and help build this grea
 
 ### Developing/Debugging
 
-- Flow Launcher's target framework is .Net 6
+- Flow Launcher's target framework is .Net 7
 
 - Install Visual Studio 2022