Bump version to 0.5.0 for new release.

PiperOrigin-RevId: 331473494

Author: nutsiepully

tensorflow_model_optimization/python/core/version.py

@@ -16,8 +16,8 @@
 
 # We follow Semantic Versioning (https://semver.org/)
 _MAJOR_VERSION = '0'
-_MINOR_VERSION = '4'
-_PATCH_VERSION = '1'
+_MINOR_VERSION = '5'
+_PATCH_VERSION = '0'
 
 # When building releases, we can update this value on the release branch to
 # reflect the current release candidate ('rc0', 'rc1') or, finally, the official