lint: Enable flake8-raise

I'm not sure I agree with not using the parens in
   raise SomeError
but being consistent is definitely better than not being consistent.

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

pyproject.toml

@@ -97,6 +97,7 @@ select = [
     "PIE", # flake8-pie
     "PYI", # flake8-pyi
     "RET", # flake8-return
+    "RSE", # flake8-raise
     "RUF", # ruff-specific rules
     "S",   # flake8-bandit
     "SIM", # flake8-simplify

tuf/ngclient/_internal/trusted_metadata_set.py

@@ -240,7 +240,7 @@ def update_timestamp(self, data: bytes) -> Timestamp:
                 )
             # Keep using old timestamp if versions are equal.
             if new_timestamp.version == self.timestamp.version:
-                raise exceptions.EqualVersionNumberError()
+                raise exceptions.EqualVersionNumberError
 
             # Prevent rolling back snapshot version
             snapshot_meta = self.timestamp.snapshot_meta