tools: allow icutrim.py to run on python2

Refs: https://github.com/nodejs/build/issues/2998

Small icu seems broken from 14.x since it uses python2. Although main no longer supports python2 landing and backporting this change to the 14.x line would allow us to simplify future backports as currently the files are the same across lines.

Signed-off-by: Michael Dawson mdawson@devrus.com