Add async python client for Delta Chat core JSON-RPC

deltachat-rpc-client/tox.ini

@@ -0,0 +1,20 @@
+[tox]
+isolated_build = true
+envlist =
+    py3
+
+[testenv]
+commands =
+    pytest {posargs}
+setenv =
+# Avoid stack overflow when Rust core is built without optimizations.
+    RUST_MIN_STACK=8388608
+    PATH = {env:PATH}{:}{toxinidir}/../target/debug
+passenv =
+    DCC_NEW_TMP_EMAIL
+deps =
+    pytest
+    pytest-async
+    pytest-asyncio
+    aiohttp
+    aiodns