Remove upper bound for Protobuf compatibility.

PiperOrigin-RevId: 752795581

Author: tfx-copybara

RELEASE.md

@@ -7,6 +7,7 @@
 ## Bug Fixes and Other Changes
 
 *   Relax dependency on Protobuf to include version 6.x
+*   Remove upper bound for Protobuf dependency
 
 ## Breaking Changes
 

setup.py

@@ -128,7 +128,7 @@ def run(self):
     install_requires=[
         'absl-py>=0.9,<3.0.0',
         'googleapis-common-protos>=1.56.4,<2;python_version>="3.11"',
-        'protobuf>=4.25.2,<7.0.0;python_version>="3.11"',
+        'protobuf>=4.25.2;python_version>="3.11"',
         'protobuf>=4.21.6,<4.22;python_version<"3.11"',
     ],
     python_requires='>=3.9,<4',