Revert "Show test issues as annotations in the GitHub Actions job summary"

This reverts commit 3a5ff35928.

Annotations were not actually appearing.
<https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions>

test/gfx/test.sh

@@ -104,7 +104,7 @@ done
 if [[ "$failed" -eq 0 ]]; then
 	echo "${bold}${green}All ${tests} tests passed!${rescolors}${resbold}"
 else
-	echo "::warning ${bold}${red}${failed} of the RGBGFX tests failed!${rescolors}${resbold}"
+	echo "${bold}${red}${failed} of the tests failed!${rescolors}${resbold}"
 fi
 
 exit $rc