Fix Python stubs

Author: fjarri

.github/workflows/umbral-pre.yml

@@ -124,7 +124,7 @@ jobs:
         run: pip install mypy ruff
 
       - name: Run mypy.stubtest
-        run: python -m mypy.stubtest umbral_pre --allowlist stubtest-allowlist.txt
+        run: python -m mypy.stubtest umbral_pre
         working-directory: umbral-pre-python
 
       - name: Run ruff

umbral-pre-python/stubtest-allowlist.txt

@@ -64,7 +64,7 @@ class PublicKey:
 @final
 class Signer:
 
-    def __init__(self, secret_key: SecretKey):
+    def __new__(cls, secret_key: SecretKey):
         ...
 
     def sign(self, message: bytes) -> Signature:
@@ -237,7 +237,7 @@ class CurvePoint:
 @final
 class Parameters:
 
-    def __init__(self) -> None:
+    def __new__(cls):
         ...
 
     u: CurvePoint
@@ -246,8 +246,8 @@ class Parameters:
 @final
 class ReencryptionEvidence:
 
-    def __init__(
-            self,
+    def __new__(
+            cls,
             capsule: Capsule,
             vcfrag: VerifiedCapsuleFrag,
             verifying_pk: PublicKey,

umbral-pre-python/umbral_pre/__init__.pyi

@@ -207,8 +207,8 @@ pub struct Signer {
 #[pymethods]
 impl Signer {
     #[new]
-    pub fn new(sk: &SecretKey) -> Self {
-        umbral_pre::Signer::new(sk.backend.clone()).into()
+    pub fn new(secret_key: &SecretKey) -> Self {
+        umbral_pre::Signer::new(secret_key.backend.clone()).into()
     }
 
     pub fn sign(&self, message: &[u8]) -> Signature {