Xenial: Fix python packaging

Updated MarkupSafe from 1.0 to 1.1.0, this version is incompatible with
setuptools.

Change-Id: I5efdb20055ac72523e6b8be1427ac29907d6ec39
Signed-off-by: Benjamin Copeland <ben.copeland@linaro.org>
diff --git a/xenial-amd64-tf-m-build/requirements_python3.txt b/xenial-amd64-tf-m-build/requirements_python3.txt
index 51d3cd3..507db57 100644
--- a/xenial-amd64-tf-m-build/requirements_python3.txt
+++ b/xenial-amd64-tf-m-build/requirements_python3.txt
@@ -1,7 +1,7 @@
 cbor==1.0.0
 cryptography==2.7
 Jinja2==2.10
-MarkupSafe==1.0
+MarkupSafe==1.1.0
 PyYAML==3.12
 pycryptodome==3.6.6
 pyasn1==0.1.9