Pipeline Info - Timeline - Inconsistent verical alignment (#6767)

Sourced the fix from the original maintainer
jiahuang/d3-timeline@8439407

The nextflow repo where this code was originally sourced from is long abandoned and archived
https://github.com/nextflow-io/d3-timeline

Signed-off-by: Peter Kneale <peterkneale@gmail.com>

Author: PeterKneale

modules/nextflow/src/main/resources/nextflow/trace/assets/d3-timeline.js

@@ -154,7 +154,7 @@
 
     var appendLabel = function (gParent, yAxisMapping, index, hasLabel, datum) {
       var fullItemHeight    = itemHeight + itemMargin;
-      var rowsDown          = fullItemHeight + fullItemHeight * (yAxisMapping[index] || 1);
+      var rowsDown          = margin.top + (fullItemHeight/2) + fullItemHeight * (yAxisMapping[index] || 1);
 
       gParent.append("text")
         .attr("class", "timeline-label")