Update module github.com/go-sql-driver/mysql to v1.9.1 (forgejo) (#7293)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [github.com/go-sql-driver/mysql](https://github.com/go-sql-driver/mysql) | require | minor | `v1.8.1` -> `v1.9.1` |

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### Release Notes

<details>
<summary>go-sql-driver/mysql (github.com/go-sql-driver/mysql)</summary>

### [`v1.9.1`](https://github.com/go-sql-driver/mysql/blob/HEAD/CHANGELOG.md#v191-2025-03-21)

[Compare Source](https://github.com/go-sql-driver/mysql/compare/v1.9.0...v1.9.1)

##### Major Changes

- Add Charset() option. ([#&#8203;1679](https://github.com/go-sql-driver/mysql/issues/1679))

##### Bugfixes

- go.mod: fix go version format ([#&#8203;1682](https://github.com/go-sql-driver/mysql/issues/1682))
- Fix FormatDSN missing ConnectionAttributes ([#&#8203;1619](https://github.com/go-sql-driver/mysql/issues/1619))

### [`v1.9.0`](https://github.com/go-sql-driver/mysql/blob/HEAD/CHANGELOG.md#v190-2025-02-18)

[Compare Source](https://github.com/go-sql-driver/mysql/compare/v1.8.1...v1.9.0)

##### Major Changes

- Implement zlib compression. ([#&#8203;1487](https://github.com/go-sql-driver/mysql/issues/1487))
- Supported Go version is updated to Go 1.21+. ([#&#8203;1639](https://github.com/go-sql-driver/mysql/issues/1639))
- Add support for VECTOR type introduced in MySQL 9.0. ([#&#8203;1609](https://github.com/go-sql-driver/mysql/issues/1609))
- Config object can have custom dial function. ([#&#8203;1527](https://github.com/go-sql-driver/mysql/issues/1527))

##### Bugfixes

- Fix auth errors when username/password are too long. ([#&#8203;1625](https://github.com/go-sql-driver/mysql/issues/1625))
- Check if MySQL supports CLIENT_CONNECT_ATTRS before sending client attributes. ([#&#8203;1640](https://github.com/go-sql-driver/mysql/issues/1640))
- Fix auth switch request handling. ([#&#8203;1666](https://github.com/go-sql-driver/mysql/issues/1666))

##### Other changes

- Add "filename:line" prefix to log in go-mysql. Custom loggers now show it. ([#&#8203;1589](https://github.com/go-sql-driver/mysql/issues/1589))
- Improve error handling. It reduces the "busy buffer" errors. ([#&#8203;1595](https://github.com/go-sql-driver/mysql/issues/1595), [#&#8203;1601](https://github.com/go-sql-driver/mysql/issues/1601), [#&#8203;1641](https://github.com/go-sql-driver/mysql/issues/1641))
- Use `strconv.Atoi` to parse max_allowed_packet. ([#&#8203;1661](https://github.com/go-sql-driver/mysql/issues/1661))
- `rejectReadOnly` option now handles ER_READ_ONLY_MODE (1290) error too. ([#&#8203;1660](https://github.com/go-sql-driver/mysql/issues/1660))

</details>

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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7293
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Renovate Bot <forgejo-renovate-action@forgejo.org>
Co-committed-by: Renovate Bot <forgejo-renovate-action@forgejo.org>