Update Rust crate diesel to 2.1.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
diesel (source)	dev-dependencies	minor	2.0.4 -> 2.1.0
diesel (source)	dependencies	minor	2.0.4 -> 2.1.0

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Release Notes

diesel-rs/diesel

### [`v2.1.0`](https://togithub.com/diesel-rs/diesel/blob/HEAD/CHANGELOG.md#​210-2023-05-26) [Compare Source](https://togithub.com/diesel-rs/diesel/compare/v2.0.4...v2.1.0) ##### Changed - The minimal officially supported rustc version is now 1.65.0 ##### Added - Added the `custom_type_derives` config option to customize the derives for SQL type definitions automatically generated by Diesel CLI. - Add a `#[derive(MultiConnection)]` proc-macro that lets you easily implement `diesel::Connection` for an enum of connections to different database backends. - Added a `--diff-schema` flag to the `diesel migration generate` command that generates a migration based on the difference between your database and the provided `schema.rs` file - Add a `ON CONFLICT (...) DO UPDATE ... [WHERE ...]` conditional clause support for PostgreSQL. - Add support for MySQL's `ON DUPLICATE KEY DO UPDATE` syntax through the existing upsert functions. - Add ability to define multiple columns in a single `distinct_on` for PostgreSQL, like: `.distinct_on((column_a, column_b))`. - Added column size restrictions to the generated `schema.rs` file

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