Add missing pytz requirement

pytz is used by reset_password.py but we don't have a direct dependency
on it, it's only in our requirements.txt file because celery depends on
it, which means that if celery ever removes its pytz dependency our
reset_password.py will break. Add pytz as a direct dependency to fix
this.

https://github.com/hypothesis/h/blob/f98179e4e4ca50142a06803cddc5c694eea0d5a4/h/schemas/forms/accounts/reset_password.py#L53

requirements/requirements.in

@@ -43,6 +43,7 @@ pyramid-retry
 pyramid-tm
 python-dateutil
 python-slugify < 8.1.0
+pytz
 rfc3339-validator  # Required for date-time format checking in jsonschema
 supervisor >= 4.0.0
 sqlparse

requirements/requirements.txt

@@ -178,7 +178,9 @@ python-dateutil==2.8.2
 python-slugify==8.0.1
     # via -r requirements/requirements.in
 pytz==2021.3
-    # via celery
+    # via
+    #   -r requirements/requirements.in
+    #   celery
 repoze-sendmail==4.3
     # via pyramid-mailer
 rfc3339-validator==0.1.4