fix: Update README to reference zebrad installation tag v4.3.0 (#10432)

Update README to reference zebrad installation tag v4.3.0

Author: upbqdn

README.md

@@ -90,7 +90,7 @@ cargo install --locked zebrad
 Alternatively, you can install it from GitHub:
 
 ```sh
-cargo install --git https://github.com/ZcashFoundation/zebra --tag v2.5.0 zebrad
+cargo install --git https://github.com/ZcashFoundation/zebra --tag v4.3.0 zebrad
 ```
 
 You can start Zebra by running