enhance portability (detect user-preferred bash, replace all greps with awk)

install.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Check Root User
 
@@ -66,7 +66,7 @@ install_gost() {
         ;;
     esac
     get_download_url="$base_url/tags/$version"
-    download_url=$(curl -s "$get_download_url" | grep -Eo "\"browser_download_url\": \".*${os}.*${cpu_arch}.*\"" | awk -F'["]' '{print $4}')
+    download_url=$(curl -s "$get_download_url" | awk -F'"' -v re=".*${os}.*${cpu_arch}.*" '/"browser_download_url":/ && $4 ~ re { print $4 }')
 
     # Download the binary
     echo "Downloading gost version $version..."