Update the default Pypi nightly version to 0.4.0

PiperOrigin-RevId: 447505973

Author: lu-wang-g

tensorflow_lite_support/tools/pip_package/setup.py

@@ -42,7 +42,7 @@
 # This version string is semver compatible, but incompatible with pip.
 # For pip, we will remove all '-' characters from this string, and use the
 # result for pip.
-_VERSION = '0.3.0'
+_VERSION = '0.4.0'
 
 SETUP_PACKAGES = [
     'pybind11 >= 2.6.0',