Normalize REPOSITORY_URL

[austin362667]

Normalize URLs before comparison to ensure consistent matching, regardless of trailing slashes.

This approach standardizes the URLs by either consistently adding or removing the trailing slash, allowing for flexible and accurate comparisons irrespective of user input.

For example,

const TEST_REPOSITORY_URL: &'static str = "https://test.pypi.org/legacy/";

should be the same as

const TEST_REPOSITORY_URL: &'static str = "https://test.pypi.org/legacy";

no matter there's a trailing slash at the end of url or not.

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[messense]

Thanks!