Bump MSRV to 1.70 (#11493)

This commit bumps the minimum supported rust version (MSRV) from 1.64 to
1.70. We're evaluating using new rust libraries in the Qiskit
accelerate crate that have MSRVs of 1.70 (the upstream libraries
have a higher MSRV primarily because of internal use of generic
associated types in those libraries). This commit raises the MSRV
proactively to align with the 1.0.0 release so we don't have to raise it
during a minor version release (like 1.1.0 or 1.2.0) if we chose to
start using the libraries later.

Cargo.toml

@@ -5,7 +5,7 @@ resolver = "2"
 [workspace.package]
 version = "1.0.0"
 edition = "2021"
-rust-version = "1.64"  # Keep in sync with README.md and rust-toolchain.toml.
+rust-version = "1.70"  # Keep in sync with README.md and rust-toolchain.toml.
 license = "Apache-2.0"
 
 [workspace.dependencies]

README.md

@@ -4,7 +4,7 @@
 [![Downloads](https://img.shields.io/pypi/dm/qiskit-terra.svg)](https://pypi.org/project/qiskit-terra/)
 [![Coverage Status](https://coveralls.io/repos/github/Qiskit/qiskit-terra/badge.svg?branch=main)](https://coveralls.io/github/Qiskit/qiskit-terra?branch=main)
 ![PyPI - Python Version](https://img.shields.io/pypi/pyversions/qiskit)
-[![Minimum rustc 1.64.0](https://img.shields.io/badge/rustc-1.64.0+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
+[![Minimum rustc 1.70](https://img.shields.io/badge/rustc-1.70+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
 [![Downloads](https://static.pepy.tech/badge/qiskit-terra)](https://pepy.tech/project/qiskit-terra)<!--- long-description-skip-end -->
 [![DOI](https://zenodo.org/badge/161550823.svg)](https://zenodo.org/badge/latestdoi/161550823)
 

releasenotes/notes/bump-msrv-f1449061b057cac5.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    The minimum supported Rust version for building Qiskit from source is now
+    1.70. This has been raised from the previous minimum supported Rust
+    version of 1.64 in the Qiskit 0.45.x and 0.46.0 release series.

rust-toolchain.toml

@@ -1,6 +1,6 @@
 [toolchain]
 # Keep in sync with Cargo.toml's `rust-version`.
-channel = "1.64.0"
+channel = "1.70"
 components = [
   "cargo",
   "clippy",