chore: allow custom PLAYWRIGHT_BROWSERS_PATH with Pyinstaller (microsoft#1002)

Author: mxschmitt

playwright/_impl/_transport.py

@@ -115,7 +115,7 @@ async def connect(self) -> None:
  # For pyinstaller
  env = os.environ.copy()
  if getattr(sys, "frozen", False):
- env["PLAYWRIGHT_BROWSERS_PATH"] = "0"
+ env.setdefault("PLAYWRIGHT_BROWSERS_PATH", "0")
 
  self._proc = await asyncio.create_subprocess_exec(
  str(self._driver_executable),