Fix up CI and update MSRV

[alex]

No description provided.

[Copilot]

Pull Request Overview

The PR raises the minimum supported Rust version (MSRV) to 1.74.0 across all crates and documentation, and adjusts CI settings accordingly.

• Bump rust-version to 1.74.0 in each Cargo.toml and README
• Add “Unreleased” changelog entry for the MSRV update
• Update CI matrix to test Rust 1.74.0, remove explicit toolchain pin, and simplify caching

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
asn1parse/Cargo.toml	Add rust-version = "1.74.0" and MSRV comment
asn1_derive/Cargo.toml	Update rust-version from 1.65.0 to 1.74.0
README.md	Update MSRV text and add “Unreleased” changelog entry
Cargo.toml	Bump root crate rust-version to 1.74.0
.github/workflows/ci.yml	Test matrix MSRV bump, remove toolchain pin, simplify cache

Comments suppressed due to low confidence (3)

.github/workflows/ci.yml:113

• Removing the explicit toolchain pin can lead to unpredictable CI behavior when the default toolchain changes. Pin the Rust version (e.g., toolchain: 1.74.0) to ensure reproducible builds.

with:

.github/workflows/ci.yml:121

• Limiting the cache to only the target directory may cause crates to be re-downloaded on each run. Consider restoring registry and git caches to speed up dependency resolution.

path: target/

asn1parse/Cargo.toml:6

• [nitpick] Comment indentation differs from other Cargo.toml files; align the # This specifies the MSRV comment with the existing style (two-space indent) for consistency.

# This specifies the MSRV