Raise the MSRV to 1.60.0

This is needed as env_logger v0.10.0 raised its MSRV to 1.60.0. For more
information please see the corresponding commit or PR:
    rust-cli/env_logger@660cf7f
    rust-cli/env_logger#248

Signed-off-by: Richard Leitner <dev@g0hl1n.net>

.github/workflows/github-ci.yml

@@ -12,7 +12,7 @@ jobs:
         rust:
           - stable
           - beta
-          - 1.56.1
+          - 1.60.0
           # - nightly
     env:
       TEST_PORT_A: /tmp/ttyS10
@@ -43,7 +43,7 @@ jobs:
         rust:
           - stable
           - beta
-          - 1.56.1
+          - 1.60.0
           # - nightly
     env:
       TEST_PORT_A: /tmp/ttyS10
@@ -81,7 +81,7 @@ jobs:
         rust:
           - stable
           - beta
-          - 1.56.1
+          - 1.60.0
           # - nightly
     env:
       TEST_PORT_A: COM10

Cargo.toml

@@ -13,7 +13,7 @@ categories = ["asynchronous", "hardware-support"]
 edition = "2018"
 
 [package.metadata]
-msrv = "1.56.1" # Used by cargo-msrv
+msrv = "1.60.0" # Used by cargo-msrv
 
 [features]
 default = []

README.md

@@ -38,7 +38,7 @@ cargo build --no-default-features
 ```
 
 ### MSRV
-The Minimum Supported Rust Version is **1.56.1** as found using [cargo-msrv](https://crates.io/crates/cargo-msrv)
+The Minimum Supported Rust Version is **1.60.0** as found using [cargo-msrv](https://crates.io/crates/cargo-msrv)
 
 ## Examples
 A few examples can be found [here](https://github.com/berkowski/mio-serial/tree/master/examples).