fix: replace tspl with native test context in test/examples.js

Migrate the request examples test from tspl to native Node.js test
runner features (t.plan, t.assert) to fix flakiness on Windows CI.

The tspl proxy reassigns the test context variable, which can cause
issues with execution context resolution on Windows when combined
with module-level after() calls for teardown hooks.

Also fix missing after() import in test/parser-issues.js.

Closes #5267

Author: mcollina

test/examples.js

@@ -1,13 +1,12 @@
 'use strict'
 
-const { tspl } = require('@matteo.collina/tspl')
 const { createServer } = require('node:http')
 const { test, after } = require('node:test')
 const { once } = require('node:events')
 const examples = require('../docs/examples/request.js')
 
 test('request examples', async (t) => {
-  t = tspl(t, { plan: 7 })
+  t.plan(7)
 
   let lastReq
   const exampleServer = createServer({ joinDuplicateHeaders: true }, (req, res) => {
@@ -48,21 +47,19 @@ test('request examples', async (t) => {
   ])
 
   await examples.getRequest(exampleServer.address().port)
-  t.strictEqual(lastReq.method, 'GET')
+  t.assert.strictEqual(lastReq.method, 'GET')
 
   await examples.postJSONRequest(exampleServer.address().port)
-  t.strictEqual(lastReq.method, 'POST')
-  t.strictEqual(lastReq.headers['content-type'], 'application/json')
+  t.assert.strictEqual(lastReq.method, 'POST')
+  t.assert.strictEqual(lastReq.headers['content-type'], 'application/json')
 
   await examples.postFormRequest(exampleServer.address().port)
-  t.strictEqual(lastReq.method, 'POST')
-  t.strictEqual(lastReq.headers['content-type'], 'application/x-www-form-urlencoded')
+  t.assert.strictEqual(lastReq.method, 'POST')
+  t.assert.strictEqual(lastReq.headers['content-type'], 'application/x-www-form-urlencoded')
 
   await examples.deleteRequest(exampleServer.address().port)
-  t.strictEqual(lastReq.method, 'DELETE')
+  t.assert.strictEqual(lastReq.method, 'DELETE')
 
   await examples.deleteRequest(errorServer.address().port)
-  t.strictEqual(lastReq.method, 'DELETE')
-
-  await t.completed
+  t.assert.strictEqual(lastReq.method, 'DELETE')
 })