docs: Correct MSRV in README

Author: gretchenfrage

.github/workflows/rust.yml

@@ -163,6 +163,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      # Note that we must also update the README when changing the MSRV
       - uses: dtolnay/[email protected]
       - uses: Swatinem/rust-cache@v2
       - run: cargo check --lib --all-features -p quinn-udp -p quinn-proto -p quinn

README.md

@@ -24,7 +24,7 @@ The project was founded by [Dirkjan Ochtman](https://github.com/djc) and
   [rustls][rustls] and [*ring*][ring]
 - Application-layer datagrams for small, unreliable messages
 - Future-based async API
-- Minimum supported Rust version of 1.66
+- Minimum supported Rust version of 1.70
 
 ## Overview