[php-src] Issue #11146: Bug in using SSE with the built-in webserver

Issue: https://github.com/php/php-src/issues/11146 Author: Yurunsoft ### Description The built-in webserver will add ";charset=UTF-8" to the end of the Content-Type response header of the SSE response The following code: ```php <?php header('Content-Type: text/event-stream'); for ($i = 0; $i < 3; ++$i) { echo 'data: ' . $i . "\n\n"; } ``` Run server: ```shell php -S 127.0.0.1:8080 test.php ``` Test: ```shell curl http://127.0.0.1:8080/ -vvv ``` Resulted in this output: ``` # curl http://127.0.0.1:8080/ -vvv * Trying 127.0.0.1:8080... * TCP_NODELAY set * Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0) > GET / HTTP/1.1 > Host: 127.0.0.1:8080 > User-Agent: curl/7.68.0 > Accept: */* > * Mark bundle as not supporting multiuse < HTTP/1.1 200 OK < Host: 127.0.0.1:8080 < Date: Fri, 28 Apr 2023 02:51:28 GMT < Connection: close < X-Powered-By: PHP/8.1.18 < Content-type: text/event-stream;charset=UTF-8 < data: 0 data: 1 data: 2 * Closing connection 0 ``` But I expected this output instead: ``` # curl http://127.0.0.1:8080/ -vvv * Trying 127.0.0.1:8080... * TCP_NODELAY set * Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0) > GET / HTTP/1.1 > Host: 127.0.0.1:8080 > User-Agent: curl/7.68.0 > Accept: */* > * Mark bundle as not supporting multiuse < HTTP/1.1 200 OK < Host: 127.0.0.1:8080 < Date: Fri, 28 Apr 2023 02:51:28 GMT < Connection: close < X-Powered-By: PHP/8.1.18 < Content-type: text/event-stream < data: 0 data: 1 data: 2 * Closing connection 0 ``` ### PHP Version PHP 8.0.28, 8.1.18, 8.2.5 ### Operating System _No response_