Does not compile with MSRV

[bryceberger]

Currently, the MSRV is:

• 1.70 according to gix/Cargo.toml
• 1.74 (nightly!) according to .github/workflows/msrv.yml
• 1.76 according to a comment in gix-commitgraph/CHANGELOG.md stating:

  Our MSRV follows the one of helix, which in turn follows Firefox

• 1.84 for all crates that are not dependents of gix (list?), according to STABILITY.md

However, gix can only build on 1.77+, due to c-string literals, used in rusqlite/rusqlite#1483. The CI passes because it only runs cargo check, which does work on 1.74.

Additionally, tests only build on 1.79+, due to rust-lang/rust#121346.

gix-macros/tests/momo/ux/error_if_ineffective.rs fails on nightly versions. This appears to be due to differences in macro source location tracking on nightly versions.

[Byron]

Thanks for bringing this to my attention!

Maybe we can start to untangle this by making the MSRV CI step perform a build instead, and use stable?

Then it seems that STABILITY.md could be changed to be less ambiguous and clarify possible differences between build and test.

Regarding gix/Cargo.toml - that can probably just be put to 1.74 like the rest of the crates.