Cyclic dependency in sqlx 0.5.9 and json feature

[cortopy]

When installing sqlx 0.5.9 with the json feature, a problem with the aHash crate comes up:

error: cyclic package dependency: package ahash v0.7.4 depends on itself. Cycle:
package ahash v0.7.4
... which is depended on by hashbrown v0.11.2
... which is depended on by indexmap v1.7.0
... which is depended on by serde_json v1.0.64
... which is depended on by wasm-bindgen v0.2.74
... which is depended on by js-sys v0.3.51
... which is depended on by getrandom v0.2.3
... which is depended on by ahash v0.7.4
Error: Process completed with exit code 101.

This is discussed in tkaitchuck/aHash#95

Currently, the only solution is to use sqlx 0.5.7. As per tkaitchuck/aHash#95 (comment) if using indexmap = "~1.6.2" the problem goes away.

Would it be possible to revert it for now in https://github.com/launchbadge/sqlx/blob/master/sqlx-core/Cargo.toml#L166

[cortopy]

I just saw there's a PR already #1501