Check that PyProj can be installed on PaaS

Previously when trying to bring in
https://github.com/alphagov/notifications-utils/pull/889 we had trouble
because there were no wheels available for the version of Pip that we
were using. Now that we have upgraded to Python 3.9 we are using a
newer buildpack which should have the necessary wheels available.

This commit is just installing the package and nothing else, to give us
more confidence that we can merge
https://github.com/alphagov/notifications-utils/pull/915/files without
having to subsequently revert it.

requirements.in

@@ -24,6 +24,7 @@ Shapely==1.7.1
 rtreelib==0.2.0
 fido2==0.9.1
 importlib-metadata==4.2.0
+pyproj==3.2.1
 
 # PaaS
 awscli-cwlogs>=1.4,<1.5

requirements.txt

@@ -28,7 +28,9 @@ botocore==1.20.84
 cachetools==4.2.2
     # via notifications-utils
 certifi==2021.5.30
-    # via requests
+    # via
+    #   pyproj
+    #   requests
 cffi==1.14.5
     # via cryptography
 chardet==4.0.0
@@ -162,6 +164,8 @@ pyparsing==2.4.7
     # via packaging
 pypdf2==1.26.0
     # via notifications-utils
+pyproj==3.2.1
+    # via -r requirements.in
 python-dateutil==2.8.1
     # via
     #   awscli-cwlogs