sha module is deprecated

This patch removes the deprecated warnings from the python
scripts.

Change-Id: I052a0aab3fb28dd1d78de1307edafda6b6c35e5f
diff --git a/tools/releasetools/check_target_files_signatures b/tools/releasetools/check_target_files_signatures
index 17aebdc..99bc801 100755
--- a/tools/releasetools/check_target_files_signatures
+++ b/tools/releasetools/check_target_files_signatures
@@ -47,12 +47,16 @@
 
 import os
 import re
-import sha
 import shutil
 import subprocess
 import tempfile
 import zipfile
 
+try:
+  from hashlib import sha1 as sha1
+except ImportError:
+  from sha import sha as sha1
+
 import common
 
 # Work around a bug in python's zipfile module that prevents opening
@@ -112,7 +116,7 @@
         self.certs[cert] = self.certs[cert] + "," + name
     else:
       if name is None:
-        name = "unknown cert %s (%s)" % (sha.sha(cert).hexdigest()[:12],
+        name = "unknown cert %s (%s)" % (sha1(cert).hexdigest()[:12],
                                          GetCertSubject(cert))
       self.certs[cert] = name