tests: port assertEquals() with delta to assertEqualsWithDelta()

assertEquals() in phpunit 9.5 no longer takes a delta parameter
and has assertEqualsWithDelta() as a replacement. This means
float get compared without a delta atm, and a recent phpunit
release (9.5.25) has made float comparisons stricter resulting in
test suite errors such as:

1) SubtaskTimeTrackingModelTest::testCalculateSubtaskTime
Total spent
Failed asserting that 3.3000000000000003 matches expected 3.3.
tests/units/Model/SubtaskTimeTrackingModelTest.php:186

This replaces all assertEquals() calls that pass a delta value
with assertEqualsWithDelta().

tests/units/Model/TaskModificationModelTest.php

@@ -240,7 +240,7 @@ class TaskModificationModelTest extends Base
         $this->assertTrue($taskModificationModel->update(array('id' => 1, 'date_started' => time())));
 
         $task = $taskFinderModel->getById(1);
-        $this->assertEquals(time(), $task['date_started'], '', 1);
+        $this->assertEqualsWithDelta(time(), $task['date_started'], 1, '');
     }
 
     public function testChangeTimeEstimated()