chore: Clarify setter to not return a value

Solves this eslint issue:

/puter/packages/phoenix/src/ansi-shell/ANSIShell.js
  86:23  error  Setter cannot return a value  no-setter-return

packages/phoenix/src/ansi-shell/ANSIShell.js

@@ -83,7 +83,7 @@ export class ANSIShell extends EventTarget {
         Object.defineProperty(this.env, 'PWD', {
             enumerable: true,
             get: () => this.variables.pwd,
-            set: v => this.variables.pwd = v
+            set: v => { this.variables.pwd = v }
         })
         Object.defineProperty(this.env, 'ROWS', {
             enumerable: true,