feat: use transition component everywhere

src/styles/common-imports.scss

@@ -16,8 +16,6 @@
 // since $tablet is defined by bulma we can just define it after importing the utilities
 $mobile: math.div($tablet, 2);
 
-@import "mixins";
-
 $family-sans-serif: 'Open Sans', Helvetica, Arial, sans-serif;
 $vikunja-font: 'Quicksand', sans-serif;
 

src/styles/mixins.scss

@@ -1,12 +0,0 @@
-/* Transitions */
-@mixin modal-transition() {
-	.modal-enter,
-	.modal-leave-active {
-		opacity: 0;
-	}
-
-	.modal-enter .modal-container,
-	.modal-leave-active .modal-container {
-		transform: scale(0.9);
-	}
-}