[mod] addition of various type hints / tbc

- pyright configuration [1]_
- stub files: types-lxml [2]_
- addition of various type hints
- enable use of new type system features on older Python versions [3]_
- ``.tool-versions`` - set python to lowest version we support (3.10.18) [4]_:
  Older versions typically lack some typing features found in newer Python
  versions.  Therefore, for local type checking (before commit), it is necessary
  to use the older Python interpreter.

.. [1] https://docs.basedpyright.com/v1.20.0/configuration/config-files/
.. [2] https://pypi.org/project/types-lxml/
.. [3] https://typing-extensions.readthedocs.io/en/latest/#
.. [4] https://mise.jdx.dev/configuration.html#tool-versions

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Format: reST

searx/botdetection/trusted_proxies.py

@@ -19,6 +19,7 @@ if t.TYPE_CHECKING:
     from _typeshed.wsgi import WSGIEnvironment
 
 
+@t.final
 class ProxyFix:
     """A middleware like the ProxyFix_ class, where the ``x_for`` argument is
     replaced by a method that determines the number of trusted proxies via the
@@ -54,7 +55,7 @@ class ProxyFix:
 
     """
 
-    def __init__(self, wsgi_app: WSGIApplication) -> None:
+    def __init__(self, wsgi_app: "WSGIApplication") -> None:
         self.wsgi_app = wsgi_app
 
     def trusted_proxies(self) -> list[IPv4Network | IPv6Network]:
@@ -84,7 +85,7 @@ class ProxyFix:
         # fallback to first address
         return x_forwarded_for[0].compressed
 
-    def __call__(self, environ: WSGIEnvironment, start_response: StartResponse) -> abc.Iterable[bytes]:
+    def __call__(self, environ: "WSGIEnvironment", start_response: "StartResponse") -> abc.Iterable[bytes]:
         # pylint: disable=too-many-statements
 
         trusted_proxies = self.trusted_proxies()