Set minimal supported Rust version to 1.77

Current code has `Option::is_none_or()` which released 2024 Oct 17,
considering old compiler environment like Ubuntu LTS, RHEL and SLES,
replaced it to:

```rust
    self.unsolicited_messages_tx.as_ref().is_none()
    || self.unsolicited_messages_tx.as_ref().map(|x| x.is_closed())
```

Set minimum supported Rust version to 1.77 to `Cargo.toml` and enabled
CI test for it.

Signed-off-by: Gris Ge <[email protected]>

Author: cathay4t

Diff for: .github/workflows/main.yml

@@ -10,15 +10,21 @@ on:
 jobs:
   ci:
     name: CI (stable)
+    strategy:
+      fail-fast: true
+      matrix:
+        include:
+          - rust_version: "stable"
+          - rust_version: "1.77"
     runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v3
 
-      - name: Install Rust Stable
+      - name: Install Rust ${{ matrix.rust_version }}
         run: |
-          rustup override set stable
-          rustup update stable
+          rustup override set ${{ matrix.rust_version }}
+          rustup update ${{ matrix.rust_version }}
 
       - name: Test with default feature
         run: cargo test

Diff for: Cargo.toml

@@ -3,6 +3,7 @@ authors = ["Corentin Henry <[email protected]>"]
 name = "netlink-proto"
 version = "0.11.4"
 edition = "2018"
+rust-version = "1.77"
 
 homepage = "https://github.com/rust-netlink/netlink-proto"
 keywords = ["netlink", "linux", "async"]

Diff for: src/connection.rs

@@ -236,11 +236,14 @@ where
             }
         }
 
+        // Rust 1.82 has Option::is_none_or() which can simplify
+        // below checks but that version is too new(2025-Jan-26).
+        // For this fundamental crate, we should consider old compiler
+        // environment like Ubuntu LTS, RHEL and SLES.
         if ready
-            || self
-                .unsolicited_messages_tx
-                .as_ref()
-                .is_none_or(|x| x.is_closed())
+            || self.unsolicited_messages_tx.as_ref().is_none()
+            || self.unsolicited_messages_tx.as_ref().map(|x| x.is_closed())
+                == Some(true)
         {
             // The channel is closed so we can drop the sender.
             let _ = self.unsolicited_messages_tx.take();