fix: re-remove extra TB dependencies introduced due to merge conflict (#593)

Reapplying #499 to remove the extra dependencies introduced by merge conflict in f6f9a97#diff-60f61ab7a8d1910d86d9fda2261620314edcae5894d5aaa236b821c7256badd7L32-R36

Author: yfang1

setup.py

@@ -29,11 +29,7 @@
 with io.open(readme_filename, encoding="utf-8") as readme_file:
  readme = readme_file.read()
 
-tensorboard_extra_require = [
- "tensorflow >=2.3.0, <=2.5.0",
- "grpcio~=1.39.0",
- "six~=1.15.0",
-]
+tensorboard_extra_require = ["tensorflow >=2.3.0, <=2.5.0"]
 metadata_extra_require = ["pandas >= 1.0.0"]
 xai_extra_require = ["tensorflow >=2.3.0, <=2.5.0"]
 full_extra_require = list(