add markdown version (last that works)

dragoncoder047 · web-flow · commit 781265ebf18a · 2022-07-21T08:25:59.000-04:00
getpelican/pelican#3019 (comment)
diff --git a/requirements.txt b/requirements.txt
@@ -1,4 +1,5 @@
 pelican
+markdown==3.3.7
 pelican-seo
 pelican-share-post
 #pelican-sitemap
