properly ignore deprecated headers field to work with prowlarr

CHANGELOG.md

@@ -4,6 +4,10 @@ Solverr follows its own [Semantic Versioning](https://semver.org/), starting at
 
 ## [Unreleased]
 
+### Fixes
+
+- **Form POST requests from Prowlarr work again, instead of failing with "Request parameter 'headers' must be a list".** 1.6.0 started checking the type of the deprecated `headers` field, which Solverr has never read and which clients send as an object; it is accepted in any shape again and still ignored.
+
 ## [1.6.0]
 
 ### Additions

src/dtos.py

@@ -77,6 +77,12 @@ def __init__(self, _dict):
     'maxTimeout': None,
     # A fractional wait is meaningful and both engines sleep on it happily.
     'waitInSeconds': (int, float),
+    # Deprecated in FlareSolverr v2 and never read by Solverr; upstream
+    # FlareSolverr only warns and ignores it. Legacy clients such as Prowlarr
+    # still send an object here (its HeadersPost), which the `list` annotation
+    # above would reject outright. Exempt it rather than break a client that
+    # isn't wrong.
+    'headers': None,
 }
 
 _TYPE_NAMES = {

src/test_request_validation.py

@@ -218,6 +218,10 @@ def test_a_boolean_is_not_accepted_as_a_number(self):
         with self.assertRaises(Exception):
             self.check(tabs_till_verify=True)
 
+    def test_the_deprecated_headers_object_is_accepted(self):
+        # Prowlarr's form POST sends this shape; the field is never read.
+        self.assertIsNone(self.check(headers={"contentType": "application/x-www-form-urlencoded"}))
+
     def test_a_numeric_max_timeout_string_is_left_to_its_own_validator(self):
         # Deliberately coerced rather than type-checked, for callers that work today.
         self.assertIsNone(self.check(maxTimeout="90000"))