Adding required module for test.

Xlsxwriter module is used in coex test to write
output into excel sheets.

Change-Id: I06cfd1242f486caa2038a38f1f9348ce4d34889c
diff --git a/acts/framework/setup.py b/acts/framework/setup.py
index 654ba5f..37fdcb8 100755
--- a/acts/framework/setup.py
+++ b/acts/framework/setup.py
@@ -35,6 +35,7 @@
     'roman',
     'scapy-python3',
     'pylibftdi',
+    'xlsxwriter'
 ]
 
 if sys.version_info < (3, ):