go_deps should fail with a clear message when 2 modules that only differ in case are used (#1954)

**What type of PR is this?**
> Bug fix

**What package or component does this PR mostly affect?**
> go_deps

**What does this PR do? Why is it needed?**
Replaces https://github.com/bazelbuild/bazel-gazelle/pull/1949

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Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>
1 file changed