Use pip-tool's pip-compile to pin all dependencies recursively

This ensures the builds are reproducible and don't suddenly fail from
one day to another due to new releases of some dependency down the
chain.

This might benefit from some documentation so everyone knows how to
add/update dependencies and re-generate that file:

    pip-compile --allow-unsafe --generate-hashes

Author: badboy

requirements.in

@@ -0,0 +1,19 @@
+awscli==1.29.7
+beautifulsoup4==4.8.2
+GitPython==3.1.41
+boto3==1.28.7
+Flask==2.3.3
+glean-parser~=14.1.0
+google-cloud-storage==2.2.1
+gsutil==5.28
+Jinja2==3.1.3
+jsonschema==3.1.1
+python-dateutil==2.8.0
+PyYAML==6.0.1
+requests==2.31.0
+requests_cache==0.5.2
+requests_file==1.4.3
+schema==0.7.1
+urllib3==1.26.18
+Werkzeug==2.3.8
+yamllint