Convert send_attempt to an int again

[DMRobertson]

A type annotation was incorrect, and this lead me to introduce a regression in Sydent 2.5.0.

This restores the old behaviour, but converts to int at the rest level rather than within the validator. It does re-introduce a spec bug, but at least it's the old behaviour.

Fixes #460.

[clokep]

Seems reasonable.

[DMRobertson]

Many thanks!

[DMRobertson]

@clokep asks:

Did you by any chance check if there are other situations similar to #460?

My response:

I haven't seen any in Sentry, but it wouldn't surprise me if there are.
I'll have a quick look in the spec to see if there are other v1 endpoints accepting non-strings.

Method:

• look through all the deprecated /v1 endpoints in https://matrix.org/docs/spec/identity_service/r0.3.0
• are there any whose request parameters are not a string?
  • https://matrix.org/docs/spec/identity_service/r0.3.0#deprecated-post-matrix-identity-api-v1-bulk-lookup takes a list of string 2-tuples, but must be given a JSON body
  • https://matrix.org/docs/spec/identity_service/r0.3.0#deprecated-post-matrix-identity-api-v1-validate-email-requesttoken is covered by this change
  • https://matrix.org/docs/spec/identity_service/r0.3.0#deprecated-post-matrix-identity-api-v1-validate-msisdn-requesttoken takes an integer send_attempt too and might be vulnerable to the same problem.
  • https://matrix.org/docs/spec/identity_service/r0.3.0#deprecated-post-matrix-identity-api-v1-3pid-unbind takes a 3PID but that's a nested object; must be given as a json body

[clokep]

matrix.org/docs/spec/identity_service/r0.3.0#deprecated-post-matrix-identity-api-v1-validate-msisdn-requesttoken takes an integer send_attempt too and might be vulnerable to the same problem.

Sounds like we should apply the same fix for this one?