Add platform/external/python/funcsigs to the manifest.

Bug: 112596689
Test: None
diff --git a/default.xml b/default.xml
index fbab2f9..1d55a17 100644
--- a/default.xml
+++ b/default.xml
@@ -302,6 +302,7 @@
   <project path="external/python/dill" name="platform/external/python/dill" groups="vts,pdk" />
   <project path="external/python/enum" name="platform/external/python/enum" groups="vts,pdk" />
   <project path="external/python/enum34" name="platform/external/python/enum34" groups="vts,pdk" />
+  <project path="external/python/funcsigs" name="platform/external/python/funcsigs" groups="pdk" />
   <project path="external/python/future" name="platform/external/python/future" groups="vts,pdk" />
   <project path="external/python/futures" name="platform/external/python/futures" groups="vts,pdk" />
   <project path="external/python/gapic-google-cloud-pubsub-v1" name="platform/external/python/gapic-google-cloud-pubsub-v1" groups="vts,pdk" />