[REFACTOR] Remove custom contains in favor of std lib impl

Author: bashhack

csrf.go

@@ -254,7 +254,7 @@ func (cs *csrf) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// HTTP methods not defined as idempotent ("safe") under RFC7231 require
 	// inspection.
-	if !contains(safeMethods, r.Method) {
+	if !slices.Contains(safeMethods, r.Method) {
 		var isPlaintext bool
 		val := r.Context().Value(PlaintextHTTPContextKey)
 		if val != nil {

helpers.go

@@ -189,18 +189,6 @@ func xorToken(a, b []byte) []byte {
 	return res
 }
 
-// contains is a helper function to check if a string exists in a slice - e.g.
-// whether a HTTP method exists in a list of safe methods.
-func contains(vals []string, s string) bool {
-	for _, v := range vals {
-		if v == s {
-			return true
-		}
-	}
-
-	return false
-}
-
 // envError stores a CSRF error in the request context.
 func envError(r *http.Request, err error) *http.Request {
 	return contextSave(r, errorKey, err)