requirements/requirements.in: It depends on grpc >= 1.30

with older version you will get errors like this accessing the CAS:
[--:--:--][][] WARNING Failed to initialize remote https://freedesktop-sdk-cache.codethink.co.uk:11001: Received http2 header with status: 404
diff --git a/requirements/requirements.in b/requirements/requirements.in
index 7f5526f..14569a3 100644
--- a/requirements/requirements.in
+++ b/requirements/requirements.in
@@ -1,5 +1,5 @@
 Click
-grpcio >= 1.10
+grpcio >= 1.30
 jinja2 >= 2.10
 pluginbase
 protobuf >= 3.6