Fix /bin/sh compatibility issue in install.sh

tools/install.sh

@@ -36,4 +36,4 @@ echo "\033[0;32m"'                        /____/                       '"\033[0m
 
 echo "\n\n \033[0;32m....is now installed.\033[0m"
 /usr/bin/env zsh
-source ~/.zshrc
+. ~/.zshrc