🐛 Fix dashboard modal clipping behind sidebar (#9233)

Backport from develop commit 510a015424b6b98529dba19cc72bdf002b8ff83a.

- Fix release notes modal appearing behind the dashboard sidebar (by @RenzoMXD)
- Change sidebar z-index from dropdown to panels layer

Signed-off-by: Andrey Antukh <niwi@niwi.nz>

CHANGES.md

@@ -10,6 +10,7 @@
 
 ### :bug: Bugs fixed
 
+- Fix release notes modal appearing behind the dashboard sidebar (by @RenzoMXD) [Github #8296](https://github.com/penpot/penpot/issues/8296)
 - Fix incorrect handling of version restore operation [Github #9041](https://github.com/penpot/penpot/pull/9041)
 
 

frontend/src/app/main/ui/dashboard/sidebar.scss

@@ -26,7 +26,7 @@
   margin: 0 var(--sp-l) 0 0;
   border-right: $b-1 solid var(--panel-border-color);
   background-color: var(--panel-background-color);
-  z-index: var(--z-index-dropdown);
+  z-index: var(--z-index-panels);
 }
 
 //SIDEBAR CONTENT COMPONENT