python: add py.typed file

It marks the package as supporting typing according to PEP 561 <https://peps.python.org/pep-0561/>

Also remove zip-safe option from setuptools configuration for deltachat-rpc-client.
It is deprecated in setuptools and not used for wheel package format according to <https://setuptools.pypa.io/en/latest/deprecated/zip_safe.html>

python/pyproject.toml

@@ -36,6 +36,11 @@ dynamic = [
 [project.entry-points.pytest11]
 "deltachat.testplugin" = "deltachat.testplugin"
 
+[tool.setuptools.package-data]
+deltachat = [
+    "py.typed"
+]
+
 [tool.setuptools_scm]
 root = ".."
 tag_regex = '^(?P<prefix>py-)?(?P<version>[^\+]+)(?P<suffix>.*)?$'