fix(protonvpn): authenticated servers data updating (#2878)

- `-proton-username` flag for cli update
- `-proton-password` flag for cli update
- `UPDATER_PROTONVPN_USERNAME` option for periodic updates
- `UPDATER_PROTONVPN_PASSWORD` option for periodic updates

internal/provider/protonvpn/updater/version.go

@@ -0,0 +1,64 @@
+package updater
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+)
+
+// getMostRecentStableTag finds the most recent proton-account stable tag version,
+// in order to use it in the x-pm-appversion http request header. Because if we do
+// fall behind on versioning, Proton doesn't like it because they like to create
+// complications where there is no need for it. Hence this function.
+func getMostRecentStableTag(ctx context.Context, client *http.Client) (version string, err error) {
+	page := 1
+	regexVersion := regexp.MustCompile(`^proton-account@(\d+\.\d+\.\d+\.\d+)$`)
+	for ctx.Err() == nil {
+		url := "https://api.github.com/repos/ProtonMail/WebClients/tags?per_page=30&page=" + fmt.Sprint(page)
+
+		request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+		if err != nil {
+			return "", fmt.Errorf("creating request: %w", err)
+		}
+		request.Header.Set("Accept", "application/vnd.github.v3+json")
+
+		response, err := client.Do(request)
+		if err != nil {
+			return "", err
+		}
+		defer response.Body.Close()
+
+		data, err := io.ReadAll(response.Body)
+		if err != nil {
+			return "", fmt.Errorf("reading response body: %w", err)
+		}
+
+		if response.StatusCode != http.StatusOK {
+			return "", fmt.Errorf("%w: %s: %s", ErrHTTPStatusCodeNotOK, response.Status, data)
+		}
+
+		var tags []struct {
+			Name string `json:"name"`
+		}
+		err = json.Unmarshal(data, &tags)
+		if err != nil {
+			return "", fmt.Errorf("decoding JSON response: %w", err)
+		}
+
+		for _, tag := range tags {
+			if !regexVersion.MatchString(tag.Name) {
+				continue
+			}
+			version := "web-account@" + strings.TrimPrefix(tag.Name, "proton-account@")
+			return version, nil
+		}
+
+		page++
+	}
+
+	return "", fmt.Errorf("%w (queried %d pages)", context.Canceled, page)
+}