chore: add #[non_exhaustive] and mutation methods to improve compatibility (#715)

* chore: add #[non_exhaustive] to reduce backwards-incompatible changes going forward

* fix: remove ProtocolVersion import

* fix: add a few more with_ mutator methods

---------

Co-authored-by: Alex Hancock <alexhancock@block.xyz>

examples/servers/src/common/calculator.rs

@@ -49,10 +49,7 @@ impl Calculator {
 #[tool_handler]
 impl ServerHandler for Calculator {
     fn get_info(&self) -> ServerInfo {
-        ServerInfo {
-            instructions: Some("A simple calculator".into()),
-            capabilities: ServerCapabilities::builder().enable_tools().build(),
-            ..Default::default()
-        }
+        ServerInfo::new(ServerCapabilities::builder().enable_tools().build())
+            .with_instructions("A simple calculator".to_string())
     }
 }