Dispose logger on extension deactivation

editors/code/src/util.ts

@@ -18,6 +18,10 @@ export const log = new class {
     private enabled = true;
     private readonly output = vscode.window.createOutputChannel("Rust Analyzer Client");
 
+    dispose() {
+        log.output.dispose();
+    }
+
     setEnabled(yes: boolean): void {
         log.enabled = yes;
     }