Update MSRV to 1.60 and test it

.github/workflows/CI.yml

@@ -67,3 +67,16 @@ jobs:
       - name: Run cargo clippy
         if: always()
         run: cargo clippy --all-features -- -D warnings
+
+  msrv:
+    name: MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v3
+
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: "1.60"
+
+      - run: cargo check --lib --all-features

Cargo.toml

@@ -9,7 +9,7 @@ readme = "README.md"
 description = "Asynchronous TLS/SSL streams for Tokio using Rustls."
 categories = ["asynchronous", "cryptography", "network-programming"]
 edition = "2018"
-rust-version = "1.56"
+rust-version = "1.60"
 
 [dependencies]
 tokio = "1.0"