ceph_volume: fix rstrip for python 3

Removing bytes literals since rstrip only supports type String or None.

Signed-off-by: Bruceforce <markus.greis@gmx.de>

library/ceph_volume.py

@@ -630,8 +630,8 @@ def run_module():
         end=str(endd),
         delta=str(delta),
         rc=rc,
-        stdout=out.rstrip(b'\r\n'),
-        stderr=err.rstrip(b'\r\n'),
+        stdout=out.rstrip('\r\n'),
+        stderr=err.rstrip('\r\n'),
         changed=changed,
     )