MacOS is locked to bash 3.2. Manually upgrade to newer versions using this script.

upgrade-bash-macos.sh

# Check current bash version
bash --version

# Install unofficial version of bash
brew install bash

# List bash binaries
which -a bash

# Whitelist new bash shell
sudo echo "/usr/local/bin/bash" >> vim /etc/shells

# Change default shell of current user
chsh -s /usr/local/bin/bash

# Change default shell of root user
sudo chsh -s /usr/local/bin/bash