Ignore TE request header on HTTP/2

See https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2.2

Fixes getsentry/sentry-symfony#533.

src/Connection/Internal/Http2ConnectionProcessor.php

@@ -1698,6 +1698,10 @@ private function generateHeaders(Request $request): array
 
         foreach ($request->getHeaders() as $field => $values) {
             foreach ($values as $value) {
+                if ($field === 'te' && $value !== 'trailers') {
+                    continue;
+                }
+
                 $headers[] = [$field, $value];
             }
         }

test/ClientHttpBinIntegrationTest.php

@@ -18,6 +18,7 @@
 use Amp\Http\Cookie\RequestCookie;
 use Amp\Http\Cookie\ResponseCookie;
 use Amp\Http\Rfc7230;
+use Amp\Http\Server\Options;
 use Amp\Http\Server\Request as ServerRequest;
 use Amp\Http\Server\RequestHandler\CallableRequestHandler;
 use Amp\Http\Server\Response as ServerResponse;
@@ -369,6 +370,26 @@ public function testReason(): \Generator
         $this->assertSame($expectedReason, $actualReason);
     }
 
+    public function testHttp2TeHeader(): \Generator
+    {
+        $this->client = $this->builder->followRedirects(0)->build();
+
+        $this->givenServer(static function () {
+            return new ServerResponse(200);
+        });
+
+        $request = $this->createRequest();
+        $request->setProtocolVersions(['2']);
+        $request->setHeader('te', 'gzip');
+
+        /** @var Response $response */
+        $response = yield $this->executeRequest($request);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertSame(200, $response->getStatus());
+        $this->assertSame($response, $response->getOriginalResponse());
+    }
+
     public function testRedirect(): \Generator
     {
         $this->client = $this->builder->followRedirects(0)->build();
@@ -802,7 +823,7 @@ protected function setUp(): void
 
     private function givenServer(callable $requestHandler): void
     {
-        $this->httpServer = new Server([$this->socket], new CallableRequestHandler($requestHandler), new NullLogger);
+        $this->httpServer = new Server([$this->socket], new CallableRequestHandler($requestHandler), new NullLogger, (new Options)->withHttp2Upgrade());
         $this->httpServer->start();
     }