fix: pluralize unit word using the maxDecimalPoints-truncated count

When maxDecimalPoints truncates a unit count to exactly 1, the rendered
number showed 1 while the word was pluralized from the raw count (for
example humanizeDuration(1500, { maxDecimalPoints: 0 }) returned
"1 seconds"). Pluralize from the normalized count that is actually
displayed so the number and word agree.

humanize-duration.js

@@ -1382,7 +1382,9 @@
       var languageWord = language[unitName];
       var word;
       if (typeof languageWord === "function") {
-        word = languageWord(unitCount);
+        // Pluralize on the rendered count: `maxDecimalPoints` may truncate 1.5 to
+        // "1", and the word must agree with what is shown.
+        word = languageWord(normalizedUnitCount);
       } else {
         word = languageWord;
       }