Update Ember Power Calendar

Author: renovate[bot]

package-lock.json

@@ -99,8 +99,8 @@
     "ember-math-helpers": "4.0.0",
     "ember-modifier": "4.1.0",
     "ember-page-title": "8.1.0",
-    "ember-power-calendar": "0.20.2",
-    "ember-power-calendar-luxon": "0.5.0",
+    "ember-power-calendar": "0.21.0",
+    "ember-power-calendar-luxon": "0.6.0",
     "ember-qunit": "7.0.0",
     "ember-resolver": "11.0.1",
     "ember-sinon-qunit": "7.4.0",