apprt/gtk: Zig 0.15 whack a mole

src/apprt/gtk/class/surface.zig

@@ -852,13 +852,13 @@ pub const Surface = extern struct {
             const body = body: {
                 const exit_code = value.exit_code orelse break :body std.fmt.allocPrintSentinel(
                     alloc,
-                    "Command took {}.",
+                    "Command took {f}.",
                     .{value.duration.round(std.time.ns_per_ms)},
                     0,
                 ) catch break :notify;
                 break :body std.fmt.allocPrintSentinel(
                     alloc,
-                    "Command took {} and exited with code {d}.",
+                    "Command took {f} and exited with code {d}.",
                     .{ value.duration.round(std.time.ns_per_ms), exit_code },
                     0,
                 ) catch break :notify;