Fix sqlparser_bench benchmark compilation

[alamb]

If you try to run the sqlparser benchmarks it fails to compile:

cd sqlparser_bench
cargo clippy --all-targets

error[E0277]: can't compare `std::string::String` with `sqlparser::ast::Statement`
  --> benches/sqlparser_bench.rs:82:13
   |
82 |             assert_eq!(formatted_query, large_statement);
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no implementation for `std::string::String == sqlparser::ast::Statement`
   |

[alamb]

I am not sure what this assert was meant to show, so I removed it.

[alamb]

It does occur to me that this is not covered by CI. Maybe we should move the benchmark binary into the normal sqlparser crate (which I think would be more standard) rather than having an entirely separate crate (sqlparser_bench) -- that would also ensure the benchmark is covered by CI tests 🤔

[alamb]

It does occur to me that this is not covered by CI. Maybe we should move the benchmark binary into the normal sqlparser crate (which I think would be more standard) rather than having an entirely separate crate (sqlparser_bench) -- that would also ensure the benchmark is covered by CI tests 🤔

• Added a CI check here: Test benchmarks and Improve benchmark README.md #1627

[iffyio]

Thanks @alamb!