Add support for Linux with glibc (#61)

* Conditionally import Glibc on Linux for fcntl calls

* Extract transport implementations into separate files

* Fix warning in test

* Add ubuntu-latest to CI test matrix

* Switch to vapor/swiftly-action for setup step

* Configure Prettier extension to format GitHub Actions workflows

* Setup with different actions depending on platform

* Rename step

* Rename job

* Update README

Tests/MCPTests/RoundtripTests.swift

@@ -127,7 +127,7 @@ struct RoundtripTests {
         let pingTask = Task {
             try await client.ping()
             // Ping doesn't return anything, so just getting here without throwing is success
-            #expect(true)  // Test passed if we reach this point
+            #expect(Bool(true))
         }
 
         try await withThrowingTaskGroup(of: Void.self) { group in