Increase z-index of ts-dropdown (#2031)

Co-authored-by: Paweł Kuna <1282324+codecalm@users.noreply.github.com>

.changeset/nine-lions-smell.md

@@ -0,0 +1,5 @@
+---
+"@tabler/core": patch
+---
+
+Increase `z-index` of `ts-dropdown` to prevent overlapping by buttons

src/scss/vendor/_tom-select.scss

@@ -42,6 +42,7 @@ $input-border-width: 1px;
   background: var(--#{$prefix}bg-surface);
   color: var(--#{$prefix}body-color);
   box-shadow: var(--#{$prefix}box-shadow-dropdown);
+  z-index: $zindex-dropdown;
 
   .option {
     padding: $dropdown-item-padding-y $dropdown-item-padding-x;