chore: change incompatible button text color to more accessible

[jarekdanielak]

Change text color on incompatible templates button.

npx @bpmn-io/sr bpmn-io/bpmn-js-element-templates#incompatible-color

Related to camunda/camunda-modeler#4766

Proposed Changes

Checklist

To ensure you provided everything we need to look at your PR:

• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}

[barmac]

Ubuntu job is failing due to missing bpmn-io/actions/setup step. I will add it directly to the PR.

[barmac]

OK so the action is already added. We need to investigate this.

[lmbateman]

No contrast issues reported by axe DevTools or WAVE! I think we're good to go.