Drop the dead source-method assert from request_method_plan

Method-override interpretation is keyed by operationId, and the contract
derives each override's sourceMethod from that same operation
(tusClientMethodOverrideModels), so after an operationId match the
source_method comparison could never fire for contract-consistent
callers — both generated call sites pass the UPLOAD_CHUNK constants
derived from the very operation the override names. This converges the
Python interpretation with the TypeScript runtime
(tusMethodOverrideForOperation over the sourceMethod-less
tusClientRuntimeMethodOverrideModels). source_method stays the
no-override fallback method, mirroring the TS plan-method fallback.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: kvz

tusclient/protocol_generated.py

@@ -439,15 +439,6 @@ def request_method_plan(operation_id, source_method, input_options=None):
         if not input_options.get(option_name, False):
             continue
 
-        if source_method != method_override['sourceMethod']:
-            raise ValueError(
-                'tus: method override expected {} for {}, got {}'.format(
-                    method_override['sourceMethod'],
-                    operation_id,
-                    source_method,
-                )
-            )
-
         return {
             'headers': {
                 method_override['headerName']: method_override['headerValue'],