fix bare exception.

Author: T4rk1n

dash/testing/browser.py

@@ -472,7 +472,7 @@ def _try_get_webdriver(self):
         """Wrapper that catches exceptions so until() can retry on transient failures."""
         try:
             return self.get_webdriver()
-        except Exception:
+        except WebDriverException:
             logger.exception("webdriver initialization failed, will retry")
             return None