msrv: bump to Rust 1.61

It was a gaffe to release memchr 2.6 with a Rust 1.60 MSRV. I had
thought we were good there, but it turns out I never actually tested it
on aarch64. On aarch64, while many of the intrinsics were stabilized by
Rust 1.60, the actual `#[target_feature(enable = "neon")]` attribute was
not enabled until Rust 1.61.

Since Rust 1.61 is just 6 weeks from Rust 1.60 and Rust 1.61 is still
pretty conservative overall (released almost over 1.5 years ago), we
just bump the MSRV to Rust 1.61 and declare the original Rust 1.60 a
bug.

Fixes #136

.github/workflows/ci.yml

@@ -194,7 +194,7 @@ jobs:
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
-        toolchain: 1.60.0
+        toolchain: 1.61.0
     - name: Basic build
       run: cargo build --verbose
     - name: Build docs

Cargo.toml

@@ -11,7 +11,7 @@ keywords = ["memchr", "char", "scan", "strchr", "string"]
 license = "Unlicense OR MIT"
 exclude = ["/bench", "/benchmarks", "/.github", "/fuzz", "/scripts", "/tmp"]
 edition = "2021"
-rust-version = "1.60"
+rust-version = "1.61"
 
 [lib]
 name = "memchr"

README.md

@@ -47,7 +47,7 @@ When a SIMD version is not available, then this crate falls back to
 
 ### Minimum Rust version policy
 
-This crate's minimum supported `rustc` version is `1.60.0`.
+This crate's minimum supported `rustc` version is `1.61.0`.
 
 The current policy is that the minimum Rust version required to use this crate
 can be increased in minor version updates. For example, if `crate 1.0` requires