Revert "Make setting category headers bold"

This reverts commit e56347501d0a61d52bfe632fbf4453d9ab083d1c.

No attached issue; Far to late in release cycle for people to circumvent the design process.

resources/themes/cura/theme.json

@@ -49,7 +49,6 @@
         },
         "setting_category": {
             "size": 1.15,
-            "bold": true,
             "family": "Open Sans"
         },
         "action_button": {