Update module spf13/viper to v1.6.2 (#272)

Update module spf13/viper to v1.6.2

Reviewed-on: https://kolaente.dev/vikunja/api/pulls/272

vendor/gopkg.in/ini.v1/helper.go

@@ -0,0 +1,24 @@
+// Copyright 2019 Unknwon
+//
+// Licensed under the Apache License, Version 2.0 (the "License"): you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package ini
+
+func inSlice(str string, s []string) bool {
+	for _, v := range s {
+		if str == v {
+			return true
+		}
+	}
+	return false
+}