Update msrv to 1.66.

.github/workflows/main.yml

@@ -1,10 +1,9 @@
 name: CI
 on:
-  # Only run when merging to master, or open/synchronize/reopen a PR.
   push:
-    branches:
-      - master
+    branches-ignore: [master]
   pull_request:
+  merge_group:
 
 jobs:
   test:
@@ -32,7 +31,7 @@ jobs:
           - build: msrv
             os: ubuntu-20.04
             # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
-            rust: 1.65.0
+            rust: 1.66.0
     steps:
     - uses: actions/checkout@v3
     - name: Install Rust

Cargo.toml

@@ -14,7 +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 = "1.65"
+rust-version = "1.66"
 
 [dependencies]
 anyhow = "1.0.71"

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 1.65.
+mdBook currently requires at least Rust version 1.66.
 
 Once you have installed Rust, the following command can be used to build and install mdBook: