minor #8314 Update phpunit_bridge.rst (temenb, javiereguiluz)

This PR was submitted for the 3.3 branch but it was merged into the 2.8 branch instead (closes #8314).

Discussion
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Update phpunit_bridge.rst

$stopwatch->stop('event_name')->getDuration() returns time in milliseconds, so original test will fail in any way.. but not only because of "However, depending on the load of the server or the processes running on your local machine, the $duration could for example be 10.000023s instead of 10s."

Commits
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47460b5 Fixed a minor syntax issue
afbbfd5 Update phpunit_bridge.rst

Author: xabbuh

components/phpunit_bridge.rst

@@ -167,14 +167,14 @@ If you have this kind of time-related tests::
             sleep(10);
             $duration = $stopwatch->stop('event_name')->getDuration();
 
-            $this->assertEquals(10, $duration);
+            $this->assertEquals(10000, $duration);
         }
     }
 
 You used the :doc:`Symfony Stopwatch Component </components/stopwatch>` to
 calculate the duration time of your process, here 10 seconds. However, depending
 on the load of the server or the processes running on your local machine, the
-``$duration`` could for example be `10.000023s` instead of `10s`.
+``$duration`` could for example be ``10.000023s`` instead of ``10s``.
 
 This kind of tests are called transient tests: they are failing randomly
 depending on spurious and external circumstances. They are often cause trouble