Follow-up to r1811083, fix building with scons 3.0.0 and Python3

* SConstruct: Append decode('utf-8) to FILE.get_contents() to avoid
  TypeError: cannot use a string pattern on a bytes-like object


git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1814604 13f79535-47bb-0310-9956-ffa450edef68
1 file changed