chore: add constraints file

testing/constraints-3.6.txt

@@ -0,0 +1,29 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
+babel==2.3.4
+colorlog==2.6.1
+google-apitools==100000.0.0
+gcloud==0.18.3
+github3.py==1.3.0
+google-api-python-client==1.7.10
+msgpack-python==0.5.6
+networkx==1.11
+kazoo==2.6.1
+oslo.utils==3.41.0
+pbr==5.4.2
+protobuf==3.9.0
+protobuf3-to-dict==0.1.5
+requests==2.22.0
+ruamel.yaml==0.16.0
+six==1.12.0
+stringcase==1.2.0
+taskflow==3.7.1
+networkx==1.11
+pypandoc==1.4
+ply==3.8
+pyyaml==5.2