[license] client/simple: SPDX-License-Identifier: AGPL-3.0-or-later

SPDX short-form identifiers to communicate license information in a simple,
efficient, portable and machine-readable manner [1]

[1] https://spdx.dev/learn/handling-license-info/

client/simple/src/less/search.less

@@ -1,6 +1,4 @@
-/*
-* SearXNG, A privacy-respecting, hackable metasearch engine
-*/
+// SPDX-License-Identifier: AGPL-3.0-or-later
 
 #search {
   padding: 0;