Update MSRV to 1.70

Author: jonathanpallant

.github/workflows/check.yml

@@ -22,8 +22,8 @@ jobs:
         run: cargo build
       - name: Clippy
         run: cargo clippy --all-targets --all-features
-      - name: Build with 1.67.1
+      - name: Build with 1.70
         run: |
           cargo clean
-          rustup update 1.67.1 --no-self-update
-          cargo +1.67.1 build
+          rustup update 1.70 --no-self-update
+          cargo +1.70 build

README.md

@@ -22,6 +22,10 @@ You can also pass `--index-template ./index-template.html` and a file called `${
 
 You can see an example of using this tool at <https://github.com/ferrous-systems/rust-training>.
 
+## MSRV
+
+We check this crate compiles with Rust 1.70.
+
 ## Changelog
 
 See [CHANGELOG.md](./CHANGELOG.md)