[chore] update viper version (#2539)

* update viper version

* removes our last uses of the slice package

* fix tests

vendor/github.com/spf13/viper/file_finder.go

@@ -0,0 +1,38 @@
+//go:build finder
+
+package viper
+
+import (
+	"fmt"
+
+	"github.com/sagikazarmark/locafero"
+)
+
+// Search all configPaths for any config file.
+// Returns the first path that exists (and is a config file).
+func (v *Viper) findConfigFile() (string, error) {
+	var names []string
+
+	if v.configType != "" {
+		names = locafero.NameWithOptionalExtensions(v.configName, SupportedExts...)
+	} else {
+		names = locafero.NameWithExtensions(v.configName, SupportedExts...)
+	}
+
+	finder := locafero.Finder{
+		Paths: v.configPaths,
+		Names: names,
+		Type:  locafero.FileTypeFile,
+	}
+
+	results, err := finder.Find(v.fs)
+	if err != nil {
+		return "", err
+	}
+
+	if len(results) == 0 {
+		return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
+	}
+
+	return results[0], nil
+}