Merge pull request #138 from OpenSourceEcon/dependabot/pip/pygments-2.15.0

Merging

Author: rickecon

requirements.txt

@@ -8,6 +8,6 @@ itsdangerous==1.1.0
 Jinja2==2.11.3
 Markdown==3.2.2
 MarkupSafe==1.1.1
-Pygments==2.7.4
+Pygments==2.15.0
 webassets==2.0
 werkzeug>=1.0.1