Changes

<!--(On Ubuntu install <code>gir1.2-webkit-2-4.0</code>) (which is webkit2 version 4.0 ) does not work! actually requires the older gir1.2-webkit-3.0 which is "webkit 1 version 3.0" and is not available on Ubuntu 20.04  If you install the newer <code>gir1.2-webkit-2-4.0</code> and change the code lines to gi.require_version('WebKit2', '4.0')from gi.repository import WebKit2 as webkit the category shows but you get the following error Traceback (most recent call last): File "/usr/lib/python3/dist-packages/gramps/gui/viewmanager.py", line 817, in __create_page page_display = page.get_display() File "/usr/lib/python3/dist-packages/gramps/gui/views/pageview.py", line 421, in get_display self.top = self.build_interface() File "/usr/lib/python3/dist-packages/gramps/gui/views/pageview.py", line 163, in build_interface self.widget = self.build_widget() File "/home/me/.gramps/gramps51/plugins/HtmlView/htmlview.py", line 350, in build_widget self.renderer = RendererWebkit() File "/home/me/.gramps/gramps51/plugins/HtmlView/htmlview.py", line 267, in __init__ self.frame = self.window.get_main_frame()AttributeError: 'WebView' object has no attribute 'get_main_frame'-->