fix: Use --reactist-content-tertiary for scale tint

This matches the todoist-web token --product-library-display-tertiary-
idle-tint (#999999), since rgba(0,0,0,0.4) on white produces the same
effective color.

Author: rmartins90

src/components/progress-bar/progress-bar.module.css

@@ -4,7 +4,7 @@
     --reactist-progressbar-radius-inner: var(--reactist-progressbar-height);
     --reactist-progressbar-track: var(--reactist-framework-fill-crest);
     --reactist-progressbar-fill: var(--reactist-bg-brand);
-    --reactist-progressbar-scale-tint: var(--reactist-content-secondary);
+    --reactist-progressbar-scale-tint: var(--reactist-content-tertiary);
     --reactist-progressbar-scale-tick-height: 8px;
     --reactist-progressbar-scale-minor-tick-opacity: 0.15;
     --reactist-progressbar-scale-major-tick-opacity: 0.35;