Ensure datatracker API calls have trailing / when needed

[jennifer-richards]

In some testing, I happened to notice that many or most calls to the datatracker API are resulting in a 301 response before hitting the correct endpoint due to a missing trailing slash:

[24/Oct/2024 08:14:19] "GET /api/rpc/doc/submitted_to_rpc HTTP/1.0" 301 0
[24/Oct/2024 08:14:19] "GET /api/rpc/doc/submitted_to_rpc/ HTTP/1.0" 200 735
[24/Oct/2024 08:14:20] "GET /api/rpc/doc/drafts/57991 HTTP/1.0" 200 459
[24/Oct/2024 08:14:23] "GET /api/rpc/doc/drafts/57991 HTTP/1.0" 200 459
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person HTTP/1.0" 301 0
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person/ HTTP/1.0" 200 49
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person HTTP/1.0" 301 0
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person/ HTTP/1.0" 200 49
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person HTTP/1.0" 301 0
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person/ HTTP/1.0" 200 49
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person HTTP/1.0" 301 0
[24/Oct/2024 08:14:23] "GET /api/rpc/subject/14733/person/ HTTP/1.0" 200 49

This may be due to some funny network settings I have to run a k8s-deployed copy of the system on my dev machine, so check that this happens in production (or even normal dev) before spending time chasing it.