fix(deps): restore dependency on python-dateutil (googleapis#1187)

* fix(deps): restore dependency on python-dateutil

* fix(deps): remove redundante proto-plus

Co-authored-by: Tim Swast <[email protected]>

Author: 2 people

setup.py

@@ -42,8 +42,8 @@
     "google-cloud-core >= 1.4.1, <3.0.0dev",
     "google-resumable-media >= 0.6.0, < 3.0dev",
     "packaging >= 14.3",
-    "proto-plus >= 1.10.0",  # For the legacy proto-based types.
     "protobuf >= 3.12.0",  # For the legacy proto-based types.
+    "python-dateutil >= 2.7.2, <3.0dev",
     "pyarrow >= 3.0.0, < 8.0dev",
     "requests >= 2.18.0, < 3.0.0dev",
 ]