maxminddb breaking changes

• 0.25.0 \u2192 0.26.0breaking

  **BREAKING CHANGE:** The `MaxMindDBError` enum has been renamed `MaxMindDbError` and variants have been renamed and refactored. For example, `IoError` is now `Io`, `InvalidDatabaseError` is now `InvalidDatabase`, `DecodingError` is now `Decoding`, `InvalidNetworkError` is now `InvalidNetwork`. The `MapError` variant has been replaced by `Mmap` (under the `mmap` feature flag). Code explicitly matching on the old variant names must be updated.

• 0.25.0 \u2192 0.26.0breaking

  **BREAKING CHANGE:** `MaxMindDbError` no longer implements `PartialEq`. This is because underlying error types like `std::io::Error` (now wrapped by the `Io` and `Mmap` variants) do not implement `PartialEq`. Code comparing errors directly using `==` or `assert_eq!` must be updated, typically by using `matches!` or by matching on the error kind and potentially its contents.

• 0.25.0 \u2192 0.26.0breaking

  Refactored `MaxMindDbError` handling using the `thiserror` crate. Variants like `Io`, `Mmap`, and `InvalidNetwork` now directly wrap the underlying error types (`std::io::Error`, `ipnetwork::IpNetworkError`).

• 0.25.0 \u2192 0.26.0breaking

  Errors wrapping underlying types (`Io`, `Mmap`, `InvalidNetwork`) now correctly implement `std::error::Error::source()`, allowing inspection of the original cause.

• 0.25.0 \u2192 0.26.0breaking

  The `Display` implementation for `MaxMindDbError` has been refined to generally show only the specific error details, often including the message from the source error, rather than prefixing with the variant name.

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