api(deltachat-rpc-client)!: replace asyncio with threads

deltachat-rpc-client/tox.ini

@@ -6,7 +6,7 @@ envlist =
 
 [testenv]
 commands =
-    pytest {posargs}
+    pytest -n6 {posargs}
 setenv =
 # Avoid stack overflow when Rust core is built without optimizations.
     RUST_MIN_STACK=8388608
@@ -14,10 +14,8 @@ passenv =
     DCC_NEW_TMP_EMAIL
 deps =
     pytest
-    pytest-asyncio
     pytest-timeout
-    aiohttp
-    aiodns
+    pytest-xdist
 
 [testenv:lint]
 skipsdist = True