Bump version to TF 2.4.0rc0, and 0.17.0

Signed-off-by: Yong Tang <[email protected]>

Author: yongtang

tensorflow_io/core/python/ops/version_ops.py

@@ -14,5 +14,5 @@
 # ==============================================================================
 """version_ops"""
 
-package = "tensorflow>=2.3.0,<2.4.0"
-version = "0.16.0"
+package = "tensorflow>=2.4.0rc0,<2.5.0"
+version = "0.17.0"