Breeze fails to run on macOS with the old version of bash

[thekiai]

Apache Airflow version:
master/HEAD (commit 99c7496)

Environment:

• Cloud provider or hardware configuration: MacBook Air (13-inch, Early 2015)
• OS (e.g. from /etc/os-release): macOS Big Sur version 11.2.2
• Install tools: git
• Others: GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin20)
  Copyright (C) 2007 Free Software Foundation, Inc.

What happened:
When I executed ./breeze initially following this section https://github.com/apache/airflow/blob/master/BREEZE.rst#installation, I got the following error.

$ ./breeze
./breeze: line 28: @: unbound variable

What you expected to happen:

The First time you run Breeze, it pulls and builds a local version of Docker images.
It should start to pull and build a local version of Docker images.

How to reproduce it:

git clone git@github.com:apache/airflow.git
cd airflow
./breeze

Anything else we need to know:
The old version of bash reports the error when there's no argument with ${@}.
https://github.com/apache/airflow/blob/master/breeze#L28