**Is your feature request related to a problem or challenge? Please describe what you are trying to do.** <!-- A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] (This section helps Arrow developers understand the context and *why* for this feature, in addition to the *what*) --> Right now, Parquet [panics](https://github.com/apache/arrow-rs/blob/c94698c561bb76a1d5bd0532c4143718a40f9e86/parquet/src/file/statistics.rs#L213) if the size of an int96 isn't 12. We should return an error message instead. **Describe the solution you'd like** <!-- A clear and concise description of what you want to happen. --> Return an error instead of panic. **Describe alternatives you've considered** <!-- A clear and concise description of any alternative solutions or features you've considered. --> We could continue to panic. **Additional context** <!-- Add any other context or screenshots about the feature request here. -->