So, today I wanted to upgrade the PHP version installed in my notebook. 7.3 was not available at the default repositories, so I had to include a new one:
$ sudo add-apt-repository ppa:ondrej/php
After which you'll refresh the cache
$ sudo apt update
Now you can install PHP7.3 normally
$ sudo apt install php7.3
And you can also install some extensions you know you'll need
sudo apt install php7.3-bcmath php7.3-bz2 php7.3-curl php7.3-gd php7.3-intl php7.3-json php7.3-mbstring php7.3-zip php7.3-fpm
My system was automatically reconfigured to use 7.3 instead of 7.2 and I can safely remove it
$ sudo apt remove php7.2
You can check the version in use with php -v
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