Use --cask for latest versions of brew

PR #2004 <https://github.com/Genymobile/scrcpy/pull/2004>
Signed-off-by: NRomain Vimont <rom@rom1v.com>

README.md

@@ -116,6 +116,10 @@ brew install scrcpy
 You need `adb`, accessible from your `PATH`. If you don't have it yet:
 
 ```bash
+# Homebrew >= 2.6.0
+brew install --cask android-platform-tools
+
+# Homebrew < 2.6.0
 brew cask install android-platform-tools
 ```