chore(all): use casers instead of strings.Title

- Add `golang.org/x/text` dependency
- Update code to use `cases.Title(language.English)`

internal/updater/providers/ipvanish/filename.go

@@ -6,11 +6,12 @@ import (
 	"strings"
 
 	"github.com/qdm12/gluetun/internal/constants"
+	"golang.org/x/text/cases"
 )
 
 var errCountryCodeUnknown = errors.New("country code is unknown")
 
-func parseFilename(fileName, hostname string) (
+func parseFilename(fileName, hostname string, titleCaser cases.Caser) (
 	country, city string, err error) {
 	const prefix = "ipvanish-"
 	s := strings.TrimPrefix(fileName, prefix)
@@ -28,11 +29,11 @@ func parseFilename(fileName, hostname string) (
 	if !ok {
 		return "", "", fmt.Errorf("%w: %s", errCountryCodeUnknown, countryCode)
 	}
-	country = strings.Title(country)
+	country = titleCaser.String(country)
 
 	if len(parts) > 1 {
 		city = strings.Join(parts[1:], " ")
-		city = strings.Title(city)
+		city = titleCaser.String(city)
 	}
 
 	return country, city, nil