[Release] Update DeepRec release version to 1.15.5+deeprec2206. (#297)

Author: liutongxuan

tensorflow/tools/pip_package/setup.py

@@ -47,7 +47,7 @@
 # result for pip.
 # Also update tensorflow/tensorflow.bzl and
 # tensorflow/core/public/version.h
-_VERSION = '1.15.5+deeprec2204'
+_VERSION = '1.15.5+deeprec2206'
 
 REQUIRED_PACKAGES = [
     'absl-py >= 0.9.0',