Fix multiple minor security vulnerabilities

Change-Id: I7c2a42c8bd025767de12ebca2573ab01d200c100
Signed-off-by: Gabriel Cuba <gcuba@whitestack.com>
diff --git a/osm_lcm/lcm_utils.py b/osm_lcm/lcm_utils.py
index 639c5ec..5817b16 100644
--- a/osm_lcm/lcm_utils.py
+++ b/osm_lcm/lcm_utils.py
@@ -236,7 +236,7 @@
         Returns:
             hex digest  (str): The hash of the charm file
         """
-        filehash = hashlib.md5()
+        filehash = hashlib.sha256()
         with open(zipped_file, mode="rb") as file:
             contents = file.read()
             filehash.update(contents)