No spinning React logo if prefers-reduced-motion (#7931)

Author: donavon

packages/cra-template/template/src/App.css

@@ -3,11 +3,16 @@
 }
 
 .App-logo {
-  animation: App-logo-spin infinite 20s linear;
   height: 40vmin;
   pointer-events: none;
 }
 
+@media (prefers-reduced-motion: no-preference) {
+  .App-logo {
+    animation: App-logo-spin infinite 20s linear;
+  }
+}
+
 .App-header {
   background-color: #282c34;
   min-height: 100vh;