- php php-pgsql php-intl libicu-dev python3-dotenv \
- python3-psycopg2 python3-psutil python3-jinja2 python3-icu git
+ php-cli php-pgsql php-intl libicu-dev python3-dotenv \
+ python3-psycopg2 python3-psutil python3-jinja2 python3-pip \
+ python3-icu python3-datrie python3-yaml git
+
+# Some of the Python packages that come with Ubuntu 20.04 are too old, so
+# install the latest version from pip:
+
+ pip3 install --user sqlalchemy GeoAlchemy2 asyncpg
+