Add a CI target on the minimum supported version of bazel (#493)
Add a CI target on the minimum supported version of bazel (#493)

This is currently 3.0.0, but given discussion that I have seen, that was
probably too aggressive.  However, until we test against our minimum
supported version, it isn't going to be reasonable to provide releases
as suggested by #415.
bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust