fix(mpris): escape Pango markup in tooltip

Fix an issue where the mpris module's tooltip failed to render
when track metadata contained unescaped XML/HTML markup characters.

This occurred because
the mpris module formatted raw strings into the tooltip template
before passing the final string directly to `set_tooltip_markup()`,
triggering GTK/Pango parsing warnings and rendering failures.

Resolve this by wrapping tooltip metadata fields
in `Glib::Markup::escape_text` before formatting,
ensuring Pango-compliant strings are always delivered to the GTK
tooltip markup.

src/modules/mpris/mpris.cpp

@@ -729,9 +729,12 @@ auto Mpris::update() -> void {
       auto tooltip_text = fmt::format(
           fmt::runtime(tooltipstr), fmt::arg("player", info.name),
           fmt::arg("status", info.status_string),
-          fmt::arg("artist", getArtistStr(info, tooltip_len_limits_)),
-          fmt::arg("title", getTitleStr(info, tooltip_len_limits_)),
-          fmt::arg("album", getAlbumStr(info, tooltip_len_limits_)),
+          fmt::arg("artist",
+                   std::string(Glib::Markup::escape_text(getArtistStr(info, tooltip_len_limits_)))),
+          fmt::arg("title",
+                   std::string(Glib::Markup::escape_text(getTitleStr(info, tooltip_len_limits_)))),
+          fmt::arg("album",
+                   std::string(Glib::Markup::escape_text(getAlbumStr(info, tooltip_len_limits_)))),
           fmt::arg("length", tooltipLength), fmt::arg("position", tooltipPosition),
           fmt::arg("dynamic", getDynamicStr(info, tooltip_len_limits_, false)),
           fmt::arg("player_icon", getIconFromJson(config_["player-icons"], info.name)),