Resistor Color tests fail once submitted

[mikeHag]

This may be a duplicate of #1411, but the errors I get do not indicate a timeout.

The test pass on my local machine but once submitted, I always get an error related to the the version of proc-macro2.

I'll provide three examples. I have tried the test on the exercism site multiple times. #1411 implies that it will eventually work but that has not been my experience.

When I had no dependency for proc-macro2:
error: failed to select a version for the requirement proc-macro2 = "^1.0.4"
candidate versions found which didn't match: 1.0.33
location searched: /opt/test-runner/local-registry index (which is replacing registry crates-io)

When I used the dependency proc-macro2 = "1.0.4":
error: failed to select a version for the requirement proc-macro2 = "^1.0.4"
candidate versions found which didn't match: 1.0.33

When I used the dependency proc-macro2 = "1.0.33":
error: failed to select a version for the requirement proc-macro2 = "^1.0.33"
candidate versions found which didn't match: 1.0.33