Make heatmap colors more distinct (#13533)

* Make heatmap colors more distinct

Fixes: https://github.com/go-gitea/gitea/issues/13529

* use opaque colors

* make first color less opaque

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

web_src/js/components/ActivityHeatmap.vue

@@ -28,11 +28,11 @@ export default {
     isLoading: true,
     colorRange: [
       'var(--color-secondary-alpha-70)',
-      'var(--color-primary-alpha-60)',
+      'var(--color-primary-light-4)',
-      'var(--color-primary-alpha-70)',
+      'var(--color-primary-light-2)',
-      'var(--color-primary-alpha-80)',
-      'var(--color-primary-alpha-90)',
       'var(--color-primary)',
+      'var(--color-primary-dark-2)',
+      'var(--color-primary-dark-4)',
     ],
     endDate: new Date(),
     values: [],