Fix flaky ObjectsChartTest::testTypeAxisUnit

mt_rand(0, 100) occasionally produced 0, which the OpenDocument 1.2
schema rejects for chart:interval-minor-divisor/chart:interval-major,
failing RelaxNG validation with a confusing unrelated-looking error.
Use mt_rand(1, 100) instead.

Author: seanlynchwv

tests/PhpPresentation/Tests/Writer/ODPresentation/ObjectsChartTest.php

@@ -578,7 +578,7 @@ public function testTypeAxisTickLabelPosition(): void
 
     public function testTypeAxisUnit(): void
     {
-        $value = mt_rand(0, 100);
+        $value = mt_rand(1, 100);
 
         $series = new Series('Downloads', $this->seriesData);
         $line = new Line();