Add a pip requirements file for the scripts

jenkins.sh

@@ -4,12 +4,7 @@ set -ex
 
 virtualenv env
 . env/bin/activate
-pip install \
-    docutils \
-    pygments \
-    Jinja2 \
-    jsonschema \
-    PyYAML
+pip install -r scripts/requirements.txt
 
 # do sanity checks on the examples and swagger
 (cd event-schemas/ && ./check_examples.py)

scripts/requirements.txt

@@ -0,0 +1,8 @@
+# no doubt older versions would be fine for many of these but these were
+# current at the time of writing
+
+docutils >= 0.14
+pygments >= 2.2.0
+Jinja2 >= 2.9.6
+jsonschema >= 2.6.0
+PyYAML >= 3.12