Removing boto requirement

boto is not needed.

Change-Id: I8fd77df3aa0e6d67588bf3c51d1e29cc4e9e713c
diff --git a/requirements.txt b/requirements.txt
index 02fa221..01a26ba 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,6 @@
 Babel>=1.3
 # tempest>=6.0.0
 oslo.config>=2.3.0
-boto>=2.32.1
 oslo.log>=1.8.0 # Apache-2.0
 six>=1.9.0
 tempest>=10.0.0