Pin build deps to avoid MSRV bump

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
 
         include:
           # Run check with MSRV as well
-          - rust: 1.65.0
+          - rust: 1.60.0
 
     steps:
       - uses: actions/checkout@v2

Cargo.toml

@@ -33,6 +33,12 @@ critical-section = "1.1"
 
 [build-dependencies]
 riscv-target = "0.1.2"
+# riscv-target depends on regex, which depends on memchr.
+# memchr bumped it's MSRV to 1.61 midway through 2.6.x releases
+# regex increased it's MSRV to 1.65 in release 1.10.x
+# pinning regex to 1.9.6 and memchr to 2.5 until we bump our MSRV above 1.60
+regex = "=1.9.6"
+memchr = "=2.5"
 
 [features]
 default = ["critical-section-impl"]

README.md

@@ -6,7 +6,7 @@ Matrix: [#bl602-rust:matrix.org](https://matrix.to/#/#bl602-rust:matrix.org)
 
 ## Minimum Supported Rust Version
 
-The minimum supported Rust version (MSRV) for this project is Rust **v1.65.0**. The
+The minimum supported Rust version (MSRV) for this project is Rust **v1.60.0**. The
 project might build on earlier versions, but this is the earliest version that
 is expected to work.