update mermaid to 9.0.0 and enable gitGraph diagrams

www/common/diffMarked.js

@@ -201,7 +201,7 @@ define([
 
     renderer.code = function (code, language) {
         if (!code || typeof(code) !== 'string' || !code.trim()) { return defaultCode.apply(renderer, arguments); }
-        if (language === 'mermaid' && code.match(/^(flowchart|graph|pie|gantt|sequenceDiagram|classDiagram|gitGraph|stateDiagram|erDiagram|journey|requirementDiagram)/)) {
+        if (language === 'mermaid' && code.match(/^(flowchart|graph|pie|gantt|sequenceDiagram|classDiagram|gitGraph|stateDiagram|erDiagram|journey|requirementDiagram|GitGraph)/)) {
             return '<pre class="mermaid" data-plugin="mermaid">'+Util.fixHTML(code)+'</pre>';
         } else if (language === 'markmap') {
             return '<pre class="markmap" data-plugin="markmap">'+Util.fixHTML(code)+'</pre>';

www/lib/changelog.md

@@ -8,6 +8,6 @@ This file is intended to be used as a log of what third-party source we have ven
 * [jscolor v2.0.5](https://jscolor.com/) for providing a consistent color picker across all browsers
 * [jquery.ui 1.12.1](https://jqueryui.com/) for its 'autocomplete' extension which is used for our tag picker
 * [pdfjs](https://mozilla.github.io/pdf.js/) with some minor modifications to prevent CSP errors
-* [mermaid 8.13.10](https://github.com/mermaid-js/mermaid/releases/tag/8.13.4) extends our markdown integration to support a variety of diagram types
+* [mermaid 9.0.0](https://github.com/mermaid-js/mermaid/releases/tag/8.13.4) extends our markdown integration to support a variety of diagram types
 * [Fabricjs 4.6.0](https://github.com/fabricjs/fabric.js) and [Fabric-history](https://github.com/lyzerk/fabric-history) for the whiteboard app