Apply suggestion from @aristath

Author: aristath

readme.txt

@@ -1,7 +1,7 @@
 === Comment-free zone by Progress Planner ===
 Contributors: progressplanner, joostdevalk, aristath, mariekerakt, irisguelen, samalderson
 Tags: planning, maintenance, writing, blogging
-Requires at least: 6.3
+Requires at least: 6.7
 Tested up to: 6.9
 Requires PHP: 7.4
 Stable tag: 1.0.1