Pin Flask to less than version 2

Flask 2.0 requires Jinja 3.0

govuk_frontend_jinja is not compatible with Jinja 3.0 yet

requirements.in

@@ -4,7 +4,7 @@
 ago==0.0.93
 govuk-bank-holidays==0.8
 humanize==3.6.0
-Flask==2.0.1
+Flask==1.1.2  # pyup: <2
 Flask-WTF==0.15.1
 Flask-Login==0.5.0
 
@@ -24,14 +24,14 @@ fido2==0.9.1
 
 # PaaS
 awscli-cwlogs>=1.4,<1.5
-itsdangerous==2.0.1
+itsdangerous==1.1.0  # pyup: <2
 
 git+https://github.com/alphagov/notifications-utils.git@44.2.2#egg=notifications-utils==44.2.2
 git+https://github.com/alphagov/govuk-frontend-jinja.git@v0.5.8-alpha#egg=govuk-frontend-jinja==0.5.8-alpha
 
 # cryptography 3.4+ incorporates Rust code, which isn't supported on PaaS
 # e.g. https://github.com/alphagov/notifications-api/pull/3126
-cryptography==3.4.7
+cryptography<3.4 # pyup: ignore
 
 # gds-metrics requires prometheseus 0.2.0, override that requirement as later versions bring significant performance gains
 # version 0.10.0 introduced exceptions when workers crashed due to deprecating lower case `prometheus_multiproc_dir`.