appveyor - don't include credentials in DSN

as the tests don't expect it to do anything - which it does since PR php#2684

Author: SjonHortensius

appveyor/test_task.bat

@@ -27,7 +27,7 @@ set PDO_MYSQL_TEST_USER=%MYSQL_TEST_USER%
 set PDO_MYSQL_TEST_PASS=%MYSQL_PWD%
 set PDO_MYSQL_TEST_HOST=%MYSQL_TEST_HOST%
 set PDO_MYSQL_TEST_PORT=%MYSQL_TEST_PORT%
-set PDO_MYSQL_TEST_DSN=mysql:host=%PDO_MYSQL_TEST_HOST%;port=%PDO_MYSQL_TEST_PORT%;dbname=test;user=%PDO_MYSQL_TEST_USER%;password=%MYSQL_PW%
+set PDO_MYSQL_TEST_DSN=mysql:host=%PDO_MYSQL_TEST_HOST%;port=%PDO_MYSQL_TEST_PORT%;dbname=test
 "C:\Program Files\MySql\MySQL Server 5.7\bin\mysql.exe" --user=%MYSQL_TEST_USER% -e "CREATE DATABASE IF NOT EXISTS test"
 if %errorlevel% neq 0 exit /b 3