Add MSRV

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

.github/workflows/ci.yml

@@ -15,13 +15,10 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: true
-      - run: rustup update stable
-      - run: rustup component add rustfmt clippy
       - run: |
           sudo apt-get update -y
           sudo apt-get install -y libsystemd-dev
-      - run: cargo check
+      - run: cargo check --examples --tests --all-targets
       - run: cargo fmt --all -- --check --files-with-diff
       - run: cargo clippy --all-targets --all-features -- -D warnings
       - run: cargo test --all-features
-      - run: cargo build --examples --tests --all-targets

README.md

@@ -18,3 +18,6 @@ The build process as easy as:
 ```bash
 cargo build --release
 ```
+
+## Minimum supported Rust version (MSRV)
+The minimum supported version of Rust is `1.52`

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.52"
+components = ["rustfmt", "clippy"]