mautrix-telegram: fix build

With updating `pluggy` to `0.13.0`[1] the way how python modules are
imported during pytest changed which broke all modules that had a
`coding: future_fstrings` annotation at the top which used to be needed
for python <=3.5. This only affected the tests, deploying a
`mautrix-telegram` from master with `doCheck = false;` works fine.

I applied a patch for `mautrix-telegram` which drops python 3.5 compat
(this package is intended to be used as application with python 3.7, so this
should be fine on master/unstable) and modified `mautrix-appservice`
accordingly as a lot of things on master changed since their last
release, so applying a patch didn't work there.

Resolves #71996

[1] faf8cfba4e

pkgs/development/python-modules/mautrix-appservice/default.nix

@@ -9,6 +9,10 @@ buildPythonPackage rec {
     sha256 = "60192920cff75afdd096eea3a43276e33ec15f4f00bd04d2d1dda616c84f22a5";
   };
 
+  patches = lib.optional (!(pythonOlder "3.6")) [
+    ./0001-Remove-coding-annotations.patch
+  ];
+
   propagatedBuildInputs = [
     aiohttp
     future-fstrings