## Summary
Re-add the static build feature option to bundle postgres dependency
into the binary. It simplify the installation because now to run the
node the operator doesn't need to have postgres dependencies installed
on its system.
## What changed ?
* Added a `static` feature that can be activated to add the extra
dependencies during the build.
* A task that run every time a dependency has been modified so we can
make sure the build with the feature is still working correctly. (we are
assuming simple change in the code won't have an impact on it because
postgres is being used in diesel which is not a direct dependecy to
datahaven).
