External Libraries: Update the Requests library to version 2.0.8.

This is a maintenance release with minor changes:
- Only force close cURL connection when needed (cURL < 7.22).

References:
- [https://github.com/WordPress/Requests/releases/tag/v2.0.8 Requests 2.0.8 release notes]
- [WordPress/Requests@v2.0.6...v2.0.8 Full list of changes in Requests 2.0.8]

Follow-up to [54997], [55007], [55046], [55225], [55296], [55629].

Props jrf, mukesh27, spacedmonkey, costdev.
Fixes #59322.

git-svn-id: https://develop.svn.wordpress.org/trunk@56554 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/Requests/src/Requests.php

@@ -148,7 +148,7 @@ class Requests {
 	 *
 	 * @var string
 	 */
-	const VERSION = '2.0.6';
+	const VERSION = '2.0.8';
 
 	/**
 	 * Selected transport name

src/wp-includes/Requests/src/Transport/Curl.php

@@ -25,6 +25,7 @@
 final class Curl implements Transport {
 	const CURL_7_10_5 = 0x070A05;
 	const CURL_7_16_2 = 0x071002;
+	const CURL_7_22_0 = 0x071600;
 
 	/**
 	 * Raw HTTP data
@@ -363,7 +364,7 @@ private function setup_handle($url, $headers, $data, $options) {
 		$options['hooks']->dispatch('curl.before_request', [&$this->handle]);
 
 		// Force closing the connection for old versions of cURL (<7.22).
-		if (!isset($headers['Connection'])) {
+		if ($this->version < self::CURL_7_22_0 && !isset($headers['Connection'])) {
 			$headers['Connection'] = 'close';
 		}