Fix Linux compatibility and clean up compiler warnings

- Add FoundationNetworking import for Linux support in URLSessionNetworkClient
- Remove unnecessary conditional cast in InputBlock (BlockElement already conforms to Codable)
- Update README with correct repository URL

Author: diegotl

README.md

@@ -31,7 +31,7 @@ Add SlackKit to your `Package.swift` file:
 
 ```swift
 dependencies: [
-    .package(url: "https://github.com/yourusername/SlackKit.git", from: "1.0.0")
+    .package(url: "https://github.com/diegotl/SlackKit.git", from: "1.0.0")
 ]
 ```
 

Sources/SlackKit/Client/URLSessionNetworkClient.swift

@@ -1,3 +1,6 @@
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
 import Foundation
 
 // MARK: - URLSessionNetworkClient

Sources/SlackKit/Models/Blocks/InputBlock.swift

@@ -113,9 +113,7 @@ public struct InputBlock: Block {
         try container.encodeIfPresent(optional, forKey: .optional)
 
         // Encode element polymorphically
-        if let elementValue = element as? Encodable {
-            try container.encode(elementValue, forKey: .element)
-        }
+        try container.encode(element, forKey: .element)
     }
 }