Bump MSRV to 1.60

Needed for new feature syntax

.github/workflows/main.yml

@@ -31,8 +31,8 @@ jobs:
             rust: stable
           - build: msrv
             os: ubuntu-latest
-            # sync MSRV with docs: guide/src/guide/installation.md
-            rust: 1.56.0
+            # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
+            rust: 1.60.0
     steps:
     - uses: actions/checkout@master
     - name: Install Rust

Cargo.toml

@@ -14,6 +14,7 @@ license = "MPL-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
+rust-version = "1.60"
 
 [dependencies]
 anyhow = "1.0.28"

guide/src/guide/installation.md

@@ -20,7 +20,7 @@ To make it easier to run, put the path to the binary into your `PATH`.
 
 To build the `mdbook` executable from source, you will first need to install Rust and Cargo.
 Follow the instructions on the [Rust installation page].
-mdBook currently requires at least Rust version 1.56.
+mdBook currently requires at least Rust version 1.60.
 
 Once you have installed Rust, the following command can be used to build and install mdBook: