Update version numbers for TensorFlow 2.5.0-rc0

[tensorflow-jenkins]

Before merging this PR, please double check that it has correctly updated
core/public/version.h, tools/pip_package/setup.py, and
tensorflow/tensorflow.bzl. Also review the execution notes below:

Major: 2 -> 2
Minor: 5 -> 5
Patch: 0 -> 0

WARNING: Below are potentially instances of lingering old version string 
"2.5.0" in source directory "tensorflow/" that are not updated by this script. 
Please check them manually!
tensorflow/tools/pip_package/setup.py:53:2.5.0
tensorflow/tools/pip_package/setup.py:107:2.5.0
tensorflow/tools/pip_package/setup.py:119:2.5.0
tensorflow/tools/pip_package/setup.py:121:2.5.0
tensorflow/tools/pip_package/setup.py:123:2.5.0
tensorflow/lite/g3doc/guide/op_select_allowlist.md:782:2.5.0
tensorflow/lite/micro/tools/ci_build/tflm_bazel/tensorflow.bzl:11:2.5.0
Binary file 
tensorflow/lite/python/testdata/control_flow_v1_saved_model/saved_model.pb 
matches
Binary file 
tensorflow/python/compiler/tensorrt/model_tests/sample_model/saved_model.pb 
matches
tensorflow/python/keras/__init__.py:33:2.5.0
tensorflow/tensorflow.bzl:51:2.5.0

WARNING: Below are potentially instances of lingering old version string 
"2.5.0" in source directory "tensorflow/" that are not updated by this script. 
Please check them manually!
tensorflow/tools/pip_package/setup.py:53:2.5.0
tensorflow/tools/pip_package/setup.py:107:2.5.0
tensorflow/tools/pip_package/setup.py:119:2.5.0
tensorflow/tools/pip_package/setup.py:121:2.5.0
tensorflow/tools/pip_package/setup.py:123:2.5.0
tensorflow/lite/g3doc/guide/op_select_allowlist.md:782:2.5.0
tensorflow/lite/micro/tools/ci_build/tflm_bazel/tensorflow.bzl:11:2.5.0
Binary file 
tensorflow/lite/python/testdata/control_flow_v1_saved_model/saved_model.pb 
matches
Binary file 
tensorflow/python/compiler/tensorrt/model_tests/sample_model/saved_model.pb 
matches
tensorflow/python/keras/__init__.py:33:2.5.0
tensorflow/tensorflow.bzl:51:2.5.0