annotations: Set the title font color to black

In dark mode, the title is white, which clashes with the default
annotation color: yellow.

PDF documents are almost always black on white anyway, no matter whether
we're in dark mode or not, annotations colors (yellow by default) which
work well are almost always bright.

Fixes linuxmint/mint22.2-beta#7

Author: clefebvre

libview/ev-annotation-window.c

@@ -144,9 +144,10 @@ ev_annotation_window_label_changed (EvAnnotationMarkup *annot,
 				    EvAnnotationWindow *window)
 {
 	const gchar *label = ev_annotation_markup_get_label (annot);
-
+	gchar *markup_text = g_strdup_printf ("<span foreground='black'>%s</span>", label);
 	gtk_window_set_title (GTK_WINDOW (window), label);
-	gtk_label_set_text (GTK_LABEL (window->title), label);
+	gtk_label_set_markup (GTK_LABEL (window->title), markup_text);
+	g_free (markup_text);
 }
 
 static void
@@ -379,6 +380,7 @@ ev_annotation_window_constructor (GType                  type,
 	GdkRGBA            color;
 	EvRectangle        *rect;
 	gdouble             scale;
+	gchar 		   *markup_text;
 
 	object = G_OBJECT_CLASS (ev_annotation_window_parent_class)->constructor (type,
 										  n_construct_properties,
@@ -406,7 +408,12 @@ ev_annotation_window_constructor (GType                  type,
 	ev_annotation_window_set_color (window, &color);
 	gtk_widget_set_name (GTK_WIDGET (window), ev_annotation_get_name (annot));
 	gtk_window_set_title (GTK_WINDOW (window), label);
-	gtk_label_set_text (GTK_LABEL (window->title), label);
+
+	markup_text = g_strdup_printf ("<span foreground='black'>%s</span>", label);
+
+	gtk_label_set_markup (GTK_LABEL (window->title), markup_text);
+
+	g_free (markup_text);
 
 	contents = ev_annotation_get_contents (annot);
 	if (contents) {