fix(uvloop): do not throw w/ uvloop on Python 3.7 (#594)

Author: pavelfeldman

client.py

@@ -36,4 +36,9 @@ def compute_driver_executable() -> Path:
         # Prevent Python 3.7 from throwing on Linux:
         # RuntimeError: Cannot add child handler, the child watcher does not have a loop attached
         asyncio.get_event_loop()
-        asyncio.get_child_watcher()
+        try:
+            asyncio.get_child_watcher()
+        except Exception:
+            # uvloop does not support child watcher
+            # see https://github.com/microsoft/playwright-python/issues/582
+            pass