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
diff --git a/SConstruct b/SConstruct
index 5f5036b..71e5b0a 100644
--- a/SConstruct
+++ b/SConstruct
@@ -182,7 +182,7 @@
 match = re.search('SERF_MAJOR_VERSION ([0-9]+).*'
                   'SERF_MINOR_VERSION ([0-9]+).*'
                   'SERF_PATCH_VERSION ([0-9]+)',
-                  env.File('serf.h').get_contents(),
+                  env.File('serf.h').get_contents().decode('utf-8'),
                   re.DOTALL)
 MAJOR, MINOR, PATCH = [int(x) for x in match.groups()]
 env.Append(MAJOR=str(MAJOR))