fix: loosen version constraints

[chris13524]

Description

Removes specific version req's. We should be as permissive as possible, letting the downstream app customize the versions. If this library requires a specific minor version or patch, then we can use ^, ~ or * as appropriate

Resolves #44

How Has This Been Tested?

Not tested

Due Diligence

• Breaking change
• Requires a documentation update
• Requires a e2e/integration test update

[heilhead]

So what happens if relay_rpc is using features added in 1.7 release, while the consumer code forces e.g. 1.0 version?

[chris13524]

If we needed features/fixes from the 1.7 release, then we would set the minimum to 1.7 not 1 as I did

[xDarksome]

https://users.rust-lang.org/t/psa-please-specify-precise-dependency-versions-in-cargo-toml/71277

[heilhead]

Agreed with Nodar and that PSA. I don't think we should make this change, because of how cargo actually resolves dependency versions.

[chris13524]

The PSA linked actually doesn't discourage loosening version constraints like I did, but requests that when doing so that cargo +nightly -Z minimal-versions update is used in CI. Lose constraints is still good.

I added this to CI, and looks like indeed these are not appropriate version constraints. Furthermore, I tested minimal-versions against the main branch and it also fails there. Looks like (many) other crates are also lying about what versions they support.

As discussed in the thread (and the stabilization issue for the flag), fixing this requires all downstream crates getting their dependencies right. Hopefully one day we'll get there and we'll be able to install this CI and loosen our own constraints. But closing this until then.

I suppose it's slightly better that, for now, when installing a new package that you use the current version, rather than just the major version. So then you are at least not lying about what version you support. But this could still get outdated as cargo will still install the latest version of the package, which is the one you test against.