Update MSRV to 1.71

[ljoss17]

Closes: #3688

Description

Using Rust v1.70 to build Hermes will generate the following error:

cargo build --release --bin hermes
error: failed to select a version for `ibc-proto`.
    ... required by package `ibc-relayer v0.26.0`
versions that meet the requirements `^0.38.0` (locked to 0.38.0) are: 0.38.0

the package `ibc-relayer` depends on `ibc-proto`, with features: `tonic` but `ibc-proto` does not have these features.
 It has an optional dependency with that name, but that dependency uses the "dep:" syntax in the features table, so it does not have an implicit feature with that name.


failed to select a version for `ibc-proto` which could resolve this conflict

This has been fixed in Rust v1.71.0 with rust-lang/cargo#12130

---

PR author checklist:

• Added changelog entry, using unclog.
• Added tests: integration (for Hermes) or unit/mock tests (for modules).
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).
• Tagged one reviewer who will be the one responsible for shepherding this PR.

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).