reqwest Form Feature Required

Problem

When using reqwest to send form-encoded data (like OAuth token requests), the .form() method may not be available, causing confusing compiler errors that suggest the method doesn't exist.

Context / Trigger Conditions

Error messages you'll see:

error[E0599]: no method named `form` found for struct `RequestBuilder` in the current scope

or

error[E0599]: no variant or associated item named `form` found
help: there is a method `or` with a similar name