[fix] issues reported by sytlelint

"Unexpected vendor-prefixed":
   -webkit-transform & -ms-transform [3]
   -webkit-animation [2]
   @-webkit-keyframes [1]

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/@keyframes
[2] https://developer.mozilla.org/en-US/docs/Web/CSS/animation
[3] https://developer.mozilla.org/en-US/docs/Web/CSS/transform

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/static/themes/simple/src/less/toolkit_loader.less

@@ -14,33 +14,16 @@
   border-right: 1.1em solid var(--color-loading-indicator);
   border-bottom: 1.1em solid var(--color-loading-indicator);
   border-left: 1.1em solid var(--color-loading-indicator-gap);
-  -webkit-transform: translateZ(0);
-  -ms-transform: translateZ(0);
   transform: translateZ(0);
-  -webkit-animation: load8 1.1s infinite linear;
   animation: load8 1.1s infinite linear;
 }
 
-@-webkit-keyframes load8 {
-  0% {
-    -webkit-transform: rotate(0deg);
-    transform: rotate(0deg);
-  }
-
-  100% {
-    -webkit-transform: rotate(360deg);
-    transform: rotate(360deg);
-  }
-}
-
 @keyframes load8 {
   0% {
-    -webkit-transform: rotate(0deg);
     transform: rotate(0deg);
   }
 
   100% {
-    -webkit-transform: rotate(360deg);
     transform: rotate(360deg);
   }
 }