add missing pyyaml requirement

docs/admin/Installation.md

@@ -45,6 +45,7 @@ For running Nominatim:
   * [psutil](https://github.com/giampaolo/psutil)
   * [Jinja2](https://palletsprojects.com/p/jinja/)
   * [PyICU](https://pypi.org/project/PyICU/)
+  * [PyYaml](https://pyyaml.org/) (5.1+)
   * [datrie](https://github.com/pytries/datrie)
   * [PHP](https://php.net) (7.0 or later)
   * PHP-pgsql

docs/develop/Development-Environment.md

@@ -29,7 +29,7 @@ The Nominatim test suite consists of behavioural tests (using behave) and
 unit tests (using PHPUnit for PHP code and pytest for Python code).
 It has the following additional requirements:
 
-* [behave test framework](https://behave.readthedocs.io) >= 1.2.5
+* [behave test framework](https://behave.readthedocs.io) >= 1.2.6
 * [phpunit](https://phpunit.de) >= 7.3
 * [PHP CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer)
 * [Pylint](https://pylint.org/) (2.6.0 is used for the CI)

vagrant/Install-on-Centos-7.sh

@@ -42,7 +42,7 @@
                         python3-pip python3-setuptools python3-devel \
                         expat-devel zlib-devel libicu-dev
 
-    pip3 install --user psycopg2 python-dotenv psutil Jinja2 PyICU datrie
+    pip3 install --user psycopg2 python-dotenv psutil Jinja2 PyICU datrie pyyaml
 
 
 #

vagrant/Install-on-Centos-8.sh

@@ -35,7 +35,7 @@
                         python3-pip python3-setuptools python3-devel \
                         expat-devel zlib-devel libicu-dev
 
-    pip3 install --user psycopg2 python-dotenv psutil Jinja2 PyICU datrie
+    pip3 install --user psycopg2 python-dotenv psutil Jinja2 PyICU datrie pyyaml
 
 
 #

vagrant/Install-on-Ubuntu-18.sh

@@ -32,10 +32,10 @@ export DEBIAN_FRONTEND=noninteractive #DOCS:
                         php php-pgsql php-intl libicu-dev python3-pip \
                         python3-psycopg2 python3-psutil python3-jinja2 python3-icu git
 
-# The python-dotenv adn datrie package that comes with Ubuntu 18.04 is too old, so
+# Some of the Python packages that come with Ubuntu 18.04 are too old, so
 # install the latest version from pip:
 
-    pip3 install python-dotenv datrie
+    pip3 install python-dotenv datrie pyyaml
 
 #
 # System Configuration