[REF] doc: remove deprecated modules

[PEP 594] is going deprecates the `imp` standard modules in
PY3.8 in order to completely remove them in PY3.10.

The `imp` module provides the `new_module` function. It returns a new
module created solely using its name. The `types.ModuleName` is a
drop-in replacement.

Task: 2003936

[PEP 594]: https://www.python.org/dev/peps/pep-0594/\#imp

closes odoo/odoo#36463

Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

doc/_extensions/odoo_ext/pygments_override.py

@@ -118,9 +118,9 @@ class OdooStyle(Style):
         Generic.Traceback:         "",
     }
 
-import imp
+import types
 import sys
 modname = 'pygments.styles.odoo'
-m = imp.new_module(modname)
+m = types.ModuleType(modname)
 m.OdooStyle = OdooStyle
 sys.modules[modname] = m