PurlLookup does not work for Go module names containing uppercase letters

Querying for: `pkg:golang/github.com/antlr/antlr4/runtime/Go/antlr@v0.0.0-20220418222510-f25a4f6275ed` fails and returns nothing with the error:
```
{"level":"info","ts":1718224007.210796,"caller":"deps_dev/deps_dev.go:410","msg":"failed to lookup purl: pkg:golang/github.com/antlr/antlr4/runtime/Go/antlr@v0.0.0-20220418222510-f25a4f6275ed, error: rpc error: code = NotFound desc = version not found","guac-version":"v0.0.1-custom"}
```
I did the query via the new [deps.dev/api/v3alpha](http://deps.dev/api/v3alpha) and v3 and they both return the same error.

but in reality, it does exist on [deps.dev](http://deps.dev/) webpage: https://deps.dev/go/github.com%2Fantlr%2Fantlr4%2Fruntime%2FGo%2Fantlr/v0.0.0-20220418222510-f25a4f6275ed

Is there a reason for this discrepancy?