Fix raw GitHub URL in installation command

Author: [Jimmy Capizzi]

README.md

@@ -19,7 +19,7 @@ A comprehensive Linux installation script for [CLIProxyAPI](https://github.com/r
 
 ```bash
 # Download and run the installer
-curl -fsSL https://raw.githubusercontent.com/brokechubb/cliproxyapi-installer/main/cliproxyapi-installer | bash
+curl -fsSL https://raw.githubusercontent.com/brokechubb/cliproxyapi-installer/refs/heads/master/cliproxyapi-installer | bash
 
 # Or clone and run manually
 git clone https://github.com/brokechubb/cliproxyapi-installer.git
@@ -441,4 +441,4 @@ This installer script is released under the same license as CLIProxyAPI.
 
 ---
 
-**Note**: This installer is specifically for Linux systems. For other operating systems, please refer to the main CLIProxyAPI repository.
+**Note**: This installer is specifically for Linux systems. For other operating systems, please refer to the main CLIProxyAPI repository.