Pin requests due to bug with connecting to DVLA

[idavidmcdonald]

We updated requests in #4108 but we saw errors in production connecting to DVLA as per psf/requests#6730.

It looks like moving back to 2.32.2 should be unaffected, at least according to the github issue above.

Once a new version is released that fixes it, we can drop this pin. If it doesn't get fixed we could look at an alternative approach like #4113

[leohemsted]

have we been able to test this locally to confirm it's a solution?

i assume we should be able to test this by just setting up the SSL settings the same as we do in api and making a request to https://driver-vehicle-licensing.api.gov.uk/thirdparty-access/v1/authenticate and making sure it doesn't error

[idavidmcdonald]

Good point.

Verified it using the following script with versions 2.32.2 and 2.32.3 of requests. I replicate the error in 2.32.3 and get no exception in 2.32.2

from requests.adapters import HTTPAdapter
from app.clients.letter.dvla import _SpecifiedCiphersAdapter
import requests

ciphers = "TLS_AES_128_GCM_SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256"

session = requests.Session()
session.mount("https://driver-vehicle-licensing.api.gov.uk", _SpecifiedCiphersAdapter(ciphers=ciphers))
response = session.get("https://driver-vehicle-licensing.api.gov.uk/thirdparty-access/v1/authenticate")
print(response)