Tests can't compile due to rayon MSRV update without new minor bump

[CPerezz]

If you try to run the tests for this lib, you'll see that you get:

error: package rayon-core v1.11.0 cannot be built because it requires rustc 1.59 or newer, while the currently active rustc version is 1.56.0

This is due to the fact that:

❯ cargo tree -i rayon-core       
rayon-core v1.11.0
└── rayon v1.7.0
    └── criterion v0.3.6
        [dev-dependencies]
        └── bls12_381 v0.8.0 

As you can see here, criterion depends on rayon_core with ^0.3. After rayon moved up MSRV without bumping minor version, everything broke.

We might want to either:

• Bump MSRV.
• Fix Cargo.lock (doesn't make any sense to me as this is a lib).
• Downgrade Criterion in hopes it uses a version of rayon compatible with rustc 1.56.0 or older.

@str4d let me know what you prefer and I'll push a PR.

[CPerezz]

After bumping to 1.59, I saw the following:
error: package regex-syntax v0.7.2 cannot be built because it requires rustc 1.60.0 or newer, while the currently active rustc version is 1.59.0

cargo tree -i regex-syntax
regex-syntax v0.7.2
└── regex v1.8.4
    └── criterion v0.3.6
        [dev-dependencies]
        └── bls12_381 v0.8.0

It seems same thing happened as with rayon_core. Bumping to 1.60.0 solves all the issues.

[HDauven]

I'm not sure what version rayon-core is set at, but from v1.12.0 it requires at least rustc 1.63.

It would be nice if either your PR #113 and #116 were applied, or the versions locked.

[str4d]

• Fix Cargo.lock (doesn't make any sense to me as this is a lib).

As of just over a week prior to this issue being opened, the recommendation for libraries is now to check in Cargo.lock if you are trying to maintain an MSRV. I did this in #135, and tests now work again.